Grabbing a mid-season rookie call-up is always a risky fantasy proposition.  Sure, their minor league numbers may justify them joining the big league club, but until we see the players actually perform (and adapt) at the major league level, it's anyone's guess as to how these young players will do in their first taste of big league action.  Back in June, the Pirates went for the youth and called up a pair who, just recently, saw their fantasy ownership numbers jump on the back of some strong performances.  

After accumulating 106 stolen bases in 484 minor league games, Jose Tabata has been running ever since he joined the professional ranks as a 16 year old for the Yankees Gulf Coast rookie team.  He swiped a base in his major league debut and has run in just under 20% of all stolen base opportunities.  Still, he’s a little raw when it comes to reading pitchers – he’s been picked off four times – but his overall 1.7 EqBRR emphasizes his ability to take the extra base and further minimize outs on the bases.  Tabata has crossed the plate 37% of the time after initially reaching base.  That’s not a bat rate given the Pirates offense isn’t exactly… good.

It helps that Tabata has developed into an above average contact hitter.  He makes contact on 82% of his swings and puts the ball in play in 77% of his plate appearances.  With his speed, it behooves Tabata to keep the ball on the ground and that’s exactly what he’s doing with a 59% ground ball rate.  That, in turn, has helped him to achieve a .317 BABIP.  

Taking a long-term view, it’s not difficult to imagine Tabata hitting .300 some point soon while swiping a bushel of bases.  Short-term, if you’re looking for a speed boost down the stretch, Tabata will inject a little turbo into your lineup, while generating a few runs and a decent average.

His teammate Pedro Alvarez recently saw a similar uptick in ownership on the back of a week where he hit .417 and crushed four home runs and drove in nine.  Unfortunately, that has been the only decent stretch of games the 23 year old has provided since joining Pittsburgh on June 16.  Since that tear, he’s just two for his last 18.

Alvarez projects to be the classic power hitter in that he’ll hit his share of bombs while he misses his share of strikes.  In roughly a season and a half of work in the minors, he whiffed in 24% of his plate appearances while homering once every 17.7 at bats.  Since joining the Pirates, he’s powered a ball out of the park once every 18 at bats which is good news that he’s holding his own at the highest level.  However, his strikeout rate of 32% isn’t so encouraging.  Even less encouraging is that 27% of his strikes are of the swing and miss variety.  That’s the neighborhood where guys like Mark Reynolds and Adam Dunn live.  If Alvarez wants to realize that .300 BA potential, he’ll need to get out of there, and fast.

The result of so many strikeouts is just 54% of Alvarez’s plate appearances end with the ball in play.  So while his .307 BABIP is decent enough, it translates to a less than stellar .238 BA.  Still, his .277 TAv outpaces the standard .269 TAv for all major league third basemen.  But can you handle the extended dry spells in the hope he can catch fire for a week or two?

I believe in Alvarez, and he’s ideal for the keeper leagues where you can keep him on your bench while he gets some major league seasoning, but for the short-term, I’d look elsewhere.