- FanGraphs Fantasy Baseball - http://www.fangraphs.com/fantasy -

Arizona Fall League Update

The Arizona Fall League, Major League Baseball’s additional development league for prospects, is starting to wind down for 2009. Let’s have a look at some of the key prospects currently playing in the league.

Starlin Castro, SS, Chicago Cubs
The Chicago Cubs’ shortstop prospect is looking to make MLB incumbent Ryan Theriot nervous about his job security. The truth of the matter is that Castro currently projects to post similar numbers to that of Mr. Theriot. However, Castro has the edge defensively, so that could cause a shift to second base for the veteran infielder, which would then make Mike Fontenot expendable… perhaps after one more season.

In ’09, Castro hit .302/.340/.391 in high-A, where he spent the majority of the season. He also received a 31-game trial at double-A and held his own as a 19-year-old infielder by hitting .288/.347/.396. He stole 22 bases in 33 attempts in high-A – showing he needs to continue working on his base running skills – but he was perfect in six tries in double-A.

Still very young and developing, Castro looks capable of providing a .280-300 average, five to 10 homers and 20-30 steals in his prime. He’ll likely never be a run producer, and he’ll need to show a little more patience (5.0 BB% in high-A) to score a lot of runs at the top of the order. ETA: Mid-2011

Jose Tabata, OF, Pittsburgh Pirates
This former Yankees prospect has found a new lease on life in the Pirates organization. Tabata had a solid season in his first year in the organization… despite a rough start with some off-field controversy. Still just (supposedly) 21, Tabata began the year in double-A and hit .303/.370/.404 with and ISO of just .101 in 228 at-bats. Moved up to triple-A, the outfielder hit .276/.333/.410 in 134 at-bats. He did bump his ISO up to .134 and his strikeout rate remained good at 13.4%.

Unfortunately, Tabata was successful stealing bases in just 11 out 19 attempts. He’s never been a great base runner and his lower half continues to thicken up so we’re not likely to see a lot of steals in the future. This is a bad thing if Tabata’s power fails to develop, because it’s below-average for a corner outfielder (His likely destination in the Majors because he projects to lose range in center field). He has just one homer in 101 AFL at-bats. ETA: Mid-2010

Jonathan Gaston, OF, Houston Astros
Gaston may have excited more than a few fantasy-league managers in 2009 when he hit 35 homers (An out-of-this-world .320 ISO) and showed speed by stealing 14 bases and legging out 15 triples. He also hit 100 RBI and scored 119 runs, all of which would make him an extremely valuable fantasy prospect. However, he was playing in one of the best hitters’ parks in baseball and he posted a strikeout rate of 31.7 K%.

Now, many fantasy leagues won’t penalize you for strikeouts, but they will negatively impact his batting average, which was .278 in high-A ball. During the regular season, Gaston had two very hot months (May and June) when he hit for average, but he hit below .250 in April, July and August. The left-handed hitter is currently batting .111 against southpaws in the AFL in a small-sample size, but he also struggled against them in the regular season: .228/.335/.443 (.373 BABIP). Key an eye on Gaston, but don’t get too excited just yet; the 2010 season will be a big one for the Astros prospect. ETA: Mid-to-late 2011

Drew Storen, RHP, Washington Nationals
When an organization has Mike MacDougal as its closer, you know management is praying for something better to come along. Storen, a first-round draft pick from ’09, is currently rocketing through the minors and is on a collision course with the Nationals’ closer role, perhaps sooner rather than later. In ’09, he held batters to a .162 batting average while posting a strikeout rate of 11.61 K/9. He also showed solid control with a walk rate of 1.89 (although it slipped later on in the year as he tired).

Even though he posted a solid HR/9 rate of 0.47, Storen is a flyball pitcher (32.6 GB%) so he could end up being a little homer prone in the Majors. He held right-handed batters to a .111 batting average, but he was aided by a ridiculous .158 BABIP. As a fastball-slider pitcher, he may need to find a weapon to combat good left-handed hitters if he’s going to develop into an impact closer. ETA: Mid-2010