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March 19, 2008 | By Alex Eisenberg

The Most Underrated Prospects in Baseball

Over the next month or so, I will be unveiling the 2008 Prospect Preview Series (likely ending with the season already underway, but that's ok). We begin our 2008 Prospect Preview Series by looking at the most underrated prospects in all of baseball...

Henry Sosa, RHSP, San Francisco Giants (A/A+)

Age - 22
Undrafted from the Dominican Republic

Basic Stats
Advanced Stats

*Disclaimer - This article was written before knowledge that Sosa was recovering from a
torn patella tendon. The injury kept Sosa out until late May, and just returned to start his first game of the 2008 season on May 25th.

Sosa is blessed with a tremendous arm. He actually reminds me of Fautino de los Santos, a top prospect in the Oakland Athletic organization. Both came out of nowhere, both are relatively new to America and both dominated their respective leagues, which perhaps is a major reason for why both are underrated and still relatively unknown.

At single-A Augusta, Sosa gave up a microscropic 4.35 H/9 (.193 BABIP). His K% of 25.7 paints a better picture than his 8.85 K/9 because he faced so few hitters due to his dominance.

Promoted to A+ San Jose, Sosa hit a rough patch. His K% did increase slightly, but he became much more hittable (.349 BABIP). His HR rate jumped from .29 to 1.13. The biggest issues were a tendency to overthrow, which made his command suffer and his fastball to be left up in the zone. However, Sosa has the stuff to succeed at higher levels:

Fastball - ranges anywhere from 92 - 96. He doesn't have complete command of the pitch yet, but it is improving. Fastball can straighten out and he can leave it up in the zone if he overthrows it.

Grade: 60

Curveball - sits in the mid-high 80's, and has more of a splitter action to it. While the pitch can be plus at times, the question is whether he can throw the pitch for strikes.

Grade: 50

A major reason Sosa struggled in San Jose last year was because hitters laid off his curveball. As I watched clips of Sosa, I noticed he was possibly tipping off his pitches, specifically his curveball. On the left is Sosa's fastball and on the right is Sosa's curveball:

Henry Sosa throwing fastballHenry Sosa throwing curveball

Notice anything different about his lead arm in each clip at release? Perhaps this animation will explain it better:

Sosa's fastball mechanicsSosa's curveball mechanics

Sosa's lead arm hangs around his knee when he throws his curveball, while he seems to tuck his arm into his side when throwing his fastball. This is something that needs to be corrected because 1. he is possibly tipping off his pitches and 2. he doesn't display a consistent, repeatable delivery.

Change-up - comes in around 84 or 85 mph, has decent fade to it and he shows some feel for throwing it, but it still needs work and he has to develop better command of the pitch.

Henry Sosa throwing change-up

Grade: 40

Biggest Red Flag for Sosa?

His control/command. Can he throw strikes on a consistent basis? Can he get his curveball over for strikes?

Sosa's BB% was 10.5% at Augusta and jumped to 12.2% at San Jose, which is a normal increase when moving up to better levels of competition. However, his command took a major step back. He left too many of his fastballs up in the zone and couldn't consistently spot his curveball, which led to Sosa getting hit hard.

The Bottom Line

Sosa is a very raw prospect, but his upside as a #2/3 starter or a shut dow reliever out of the bullpen should have him rated higher on many prospect lists. He carries some pretty big risks, but his arm and the quality of his pitches can not be discounted.

8 Upside, Low Probability
6.5 Mid-Level, Low-Average Probability
5 Downside, Low-Average Probability

Also See: Matt Kemp's Tremendous Bat Speed, Scouting Carlos Carrasco

Jed Lowrie, SS, Boston Red Sox (AA/AAA)

Age - 24, B - B
Drafted - Round 1, 2005

Basic Stats
Advanced Stats

Lowrie's calling card is his plate discipline. He exemplifies the Boston Red Sox way. The Red Sox have shown an ability to produce quality talent from their minor league system and many of them fit the profile of Lowrie, from Kevin Youkilis to Dustin Pedroia to Jacoby Ellsbury.

Lowrie's BB% has gone from 14.2% in 2005 to 12.4% in 2006 and then all the way to 16.4% in AA-Portland last year. Lowrie is a high contact hitter that should be able to hit for at least a moderate average. He has some pop in his bat as he had a .204 ISO-power last year in AA and then continued to show solid power with a .206 ISO-power in AAA Pawtucket.

Injuries put a damper on Lowrie's 2006 season as he severely sprained his ankle in May and struggled with injuries for much of the year, which led to his overall line being less than impressive.

Lowrie's value is enhanced by being a SS, where his bat will have more value. His defense is inconsistent, and some feel he may have to move to second, but he has shown enough improvement to stay at the position. HIs arm is said to be solid, but he needs to become more accurate on his throws.

The Swing

Jed Lowrie batting Jed Lowrie

This clip doesn't exactly show Lowrie taking a clean hack at the ball so it is difficult to completely analyze his swing, but we can take a couple things from this clip:

1. Momentum Shift - you can see a shift forward in weight, which gives the hitter more momentum, and thus more power to put into their swing.

2. Short Swing - Lowrie has a short swing, which allows him to make consistent contact. He has a small loading of his hands as he drifts forward so he can keep his swing short, while maintaining the ability to hit for at least some power.

Also, it seems like he gets a little too far out in front, but I think this has more to do with the pitch. See the catcher's glove in relation to the pitch? And then see how Lowrie adjusts his swing? He plants his foot and slightly delays the opening of his hips to adjust for the breaking ball. This technique comes from hours of practice with baseball bats from

Another note is Lowrie's swing plane, which is about what you want it to be. The bat stays in the hitting zone long enough, but also allows him to get some air under the ball. This is a big reason for Lowrie's .56 GO:AO ratio.

Biggest Red Flag?

Lowrie has two red flags. The first is his defense and if he can stay at SS. Any fears were most likely pacified last year with the improvements he showed.

Does Lowrie have enough of a bat to hit? I think most would agree he does. Perhaps his poor 2006 season sticks in the back of people's minds, but he clearly battled injuries and bounced back in a big way last year.

The Bottom Line

Shortstops that can hit are difficult to find. Players that have Lowrie's plate discipline are also of a rare breed. How often can you put a player that gets on base 40% of the time in front of power hitters like David Ortiz and Manny Ramirez and put that same player at a position where offense is hard to find? Not often, but the teams that can find that kind of value in a player are the teams that ultimately win.

8 Upside, Average Probability
6 Downside, Low-Average Probability

Also See: Mid-Level to Top 10 - Who Makes the Jump?

Chase Headley, 3b, San Diego Padres (AA)

Age - 24, B - B
Round 2, 2005

Basic Stats
Advanced Stats

Headley answered critics who worried about whether he would develop enough power to hit everyday at the MLB level. After an offseason that saw Headley put on 15 pounds of muscle, he broke out in AA San Antonio as he put up an OPS of 1.017 and an ISO-power of .250, which was 107 points better from the previous year.

Headley already had excellent plate discipline as he posted BB%'s of 13.1, 13, and 15.3 the last three years, respectively. He also hit for average last year (.330) as he made consistent, hard contact. His LD% was a pretty insane 24% last year. I do believe San Antonio's score keeper may be a little more leniant than normal because the team had a home/road split in LD% for both hitters and pitchers. However, we know the ability is still there for Headley to hit line drives. On the road, he had a LD% of 28 and in 2006 he had a LD% of 18.

The Swing

Headley doesn't generate great bat speed, but it is solid enough. He worked to improve his bat speed by getting his hands away from his body a little more. Of course doing this does lead to a longer swing, and a few more strikeouts, but the trade off has worked just fine for Headley.

Here are swings from Headley from both sides of the plate. Keep in mind the right handed clip is missing a few frames:

Chase Headley batting right handedChase Headley batting left handed Chase Headley

On both sides of the plate, you see how he transfers his weight forward before turning on a firm front leg. On his left side swing, he lets his hands get a little too far out in front, but I've seen him do a better job of waiting on the ball.

Heading into 2007, Headley hit RHP much better than LHP, but the split disappeared last year.

Red Flags?

Headley doesn't have many weaknesses, but how much power he will eventually hit for is certainly a question mark. I think if he can hit 25 HRs with a lot of doubles, the Padres would be very happy, but Petco Park is going to make this a difficult feat.

The Bottom Line

With Headley, you are getting a third baseman with solid defense, excellent plate discipline, and somebody who will hit for average and moderate power. Players with the all-around package Headley gives you are not easy to find.

8.5 Upside, Low-Average Probability
6.5 Downside, Low Probability

Also See: Six Hitting Prospects to Watch in 2008

Jair Jurrjens, RHSP, Atlanta Braves (AA/MLB)

Age - 22
Undrafted Free Agent from the Netherlands

Basic Stats
Advanced Stats

Jurrjens has stuff that I think clashes with his numbers. He looks like he should miss more bats than he does and even generate a few more ground balls than he does. Jurrjens' GB% (which is around 50%) and his K% are fairly ordinary for the kind of stuff and command he displays. He has also been fairly hittable at each level. This may be because he is always around the plate and he does have a tendency to leave his pitches up.

Fastball - really has two of that sits at 93 or 94 mph with heavy sink and another that moves side-to-side, and sits at 89 or 90 mph. He can effectively spot his fastball with ease.

Jair Jurrjens throwing fastball Jair Jurrjens

Grade: 55 - 60

Slurve - he throws a cross between a slider and curveball. The pitch is inconsistent, but it does show some bite to and is another pitch he can command well.

Jair Jurrjens throwing slurve

Grade: 50 - 55

His change-up also can be an above average pitch at times and is another pitch he has outstanding command of.

Red Flags

Jurrjens has a couple red flags but the big one is injuries. Will Carroll from Baseball Prospectus said this about Jurrjen's, who sufferred an injury after a few starts at the MLB level:

"Although the young pitcher's shoulder appeared to do something on the mound, an MRI Sunday evening showed no damage significant enough to require surgery. You can read that as a Grade II strain, likely of the rotator cuff. Jurrjens has a history of shoulder strains in the minors, but reports that the previous pain he had was lower, while this pain is in the back. Every symptom points to an acute cuff problem as the result of seasonal fatigue, though he's at about the same innings level that he's been at the previous two seasons. Jurrjens may have a ceiling on his workload."


So, judging by his injury report, do his mechanics show anything we should be worried about? Lets take a look.

His tempo is solid and he hides the ball well. His fastball gets on you quick. But his arm action gives me major pause.

Jurrjens arm action

Notice how he loads up toward second and lets the ball pick up the elbow. This isn't a good thing. Jurrjens' current arm action leads to increased stress on the elbow and shoulder.

Jurrjens also suffers from a somewhat abrupt finish. On the plus side, he does repeat his delivery well. Jurrjens will have to make adjustments to his arm action and strengthen his rotator cuff if he is to prevent injury in the future. Jurrjens' athleticism will make this an easier thing to do.

The Bottom Line

Health is a major red flag, but with his youth and athleticism plus the combination of his good stuff and plus command, Jurrjens has the upside of a #3/2 starter, which is higher than the back of the rotation projection Jurrjens has been labeled with thus far.

8 Upside, Average Probability
6 Downside, Average Probability

Other Players to Watch

Austin Jackson, Age - 21, CF, New York Yankees (A/A+)

Basic Stats
Advanced Stats

Jackson had an unusual transition from low-A Charleston to A+ Tampa. He struggled at a lower level of competition in a park that was tougher for pitchers before exploding against better competition in a park that was better for pitchers. The differences are as follows:

1. Batting Average - .260 to .345, .335 BABIP to .395 BABIP

Jackson's LD% remained the same in Tampa, so his batting average was partly due to luck. However, Jackson does have the ability to hit for a high average.

2. ISO-Power - .114 to .221

Even with the improved batting average, Jackson showed increased power.

3. K% - 22.2 to 16.9

The cut down on strikeouts helped Jackson maintain a high batting average. Jackson did walk slightly less, but the batting average more than made up the difference.

Jackson was just 20 y/o last year, and has a projectable body. His success at Tampa carried over into fall ball in the Hawaii Baseball League. Jackson is also a plus defender in CF. If he can continue his success next year at AA, he has the potential to be a top-10 prospect next year.

Chris Tillman, Age - 20, RHSP, Baltimore Orioles (A/A+)

Basic Stats
Advanced Stats

A lot of people look at Tillman's ERA and peripherals and ask what's so special? First thing I say is to look at the ERA's of his teammates. Then I would point out that he pitched in one of minor league baseball's toughest parks for pitchers and in a hitter's league. And then I would point out his age, which is 19, and that he was the second youngest pitcher in the Cal League. If that isn't enough, it would be worth it to draw attention to how Tillman finished the season:

June - 23.3 IP, 13.1 BB%, 15.6 K%, 8.49 ERA
July - 32 IP, 6.4 BB%, 25.9 K%, 4.78 ERA
August - 34.7 IP, 9.7 BB%, 28.3 K%, 1.82 ERA

His command still needs work, but Tillman is extremely projectable with his tall and lanky frame. His above average fastball ranges from 92 - 95 with the potential to add more velocity and his curveball is a true plus pitch. His change-up still needs work, but showed improvement over the course of the year. His mechanics are clean overall and the possibility is there for Tillman to soar up the prospect rankings next year.

For more prospect scouting reports, check out this page of articles from our 2008 Prospect Preview Series

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Credit for sources used in this article: Sox Prospects,, and

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Also See...

2008 Prospect Preview Series

Franklin Morales: Where Has the Velocity Gone?

The Disconnecting Hips of Tim Lincecum

Is Clayton Kershaw Worth the?

Baseball Draft Preview: Scouting Hitter Justin Smoak

Baseball Draft Preview: Scouting Pitcher Brian Matusz


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