Anibal Sanchez is the second high profile prospect included in the Josh Beckett/Mike Lowell deal between Florida and Boston. As far as starting pitching prospects go, he was usually considered the third best in the system behind Jonathan Papelbon and Jon Lester. He appeared to be a power pitcher with very good control, which his strikeout and walk rates confirm:
As you can see, Sanchez was progressing nicely this season, his second as a professional. He is still very young (21 years old), and he could use a full season at Double-A to polish up, but the future looks good for young Anibal. Especially since his future is now in a pitcher's heaven, rather than Fenway Park.
From John Sickels' 2005 Baseball Prospect Book:
John was spot on with his comment, as Sanchez continued to pitch like he knew what he was doing, which is great when you already have three plus pitches. The only concern was injury due to workload (Sanchez had elbow surgery previously, but not Tommy John surgery as had been reported) and young Anibal seemed to hold up well. By the way, I highly recommend The Baseball Prospect Book by John Sickels to anyone with even the slightest interest in prospects. He is responsible for a great deal of my initial interest in prospects, and his website Minor League Ball is highly entertaining and informative, as is his book.