Neftali Feliz has faced all of 117 batters at the Major League level. According to swinging strike percentage, among relief pitchers with at least 20 expected innings pitched, Neftali Felix ranked 85th out of 263 eligible pitchers. According to my strike zone calculations, he ranked tied for 192nd for throwing pitches in the zone. By ground ball percentage, he was 186th. His rates have not been markedly better in the minors, even accounting for the RP/SP role differences.
He posted amazing ERA numbers in 2009 thanks in almost total part to a line drive rate of 5%, a BABIP of .185 and a HR/FB rate of 5%. Feliz might turn turn out to be better than most pitchers are reducing line drives against, but nobody is anywhere close to that good. He will allow more line drives, he will allow more hits and he will allow more home runs. And he will not continue striking out one out of every three batters with just a 10.3% swinging strike rate.
Neftali Feliz has been a slightly below average pitcher in terms of getting ground balls while showing below average control and well above average stuff. He's certainly a good prospect, but given that he's yet to debut in the rotation at the big league level and that even if he improves his control, he's unlikely to suddenly start getting more ground balls, the amount of hype he gets around here is out of proportion to his actual abilities demonstrated so far.
Yes, he throws fast. Averaging just under 96 mph with his fastball last season put him 12th in the majors, but that's going to fall is he starts throwing multiple innings. Furthermore, he's unlikely to hold onto even this level of success in the rotation throwing 70% fastballs. Feliz will probably become a pretty good pitcher down the line for Texas. The odds that he does that in the rotation are less certain and the odds that he does that in the rotation during 2010 are pretty slim.
Calm down.