Ben Davis
One of the more underrated prospects in the minors right now is San Diego's switch-hitting catcher, Ben Davis.  The Pads' selection of him #2 overall in the 1995 draft was viewed by many "experts" as a disastrous selection.  After all, he was drafted ahead of Jose Cruz Jr, Kerry Wood, Todd Helton, Geoff Jenkins, Matt Morris, Roy Halladay, Michael Barrett and Brett Tomko... and that was just in the first round.  Only 2 catchers drafted between 1980 and 1990, Ron Karkovice and Craig Biggio, had established themselves as major league regulars.  And after his poor showing in his first year of pro ball, hitting .201 and slugging .286, many more "experts" joined the chorus of Steve Chilcott chants.  For those of you too young to know who that is, he was the catcher the Mets selected #1 ahead of Reggie Jackson.  He never made it to the majors.
Fortunately for the Pads and Davis, sportswriters and talent evaluators don't play the games.  What was missed in that first year was that not only was Davis the 3rd youngest player in A-ball, but he was bothered by calcium deposits and elbow tendonitis all year.  The next year, he repeated A-ball, showing good power (17 homers & 30 doubles) and improving his batting average (.278) dramatically.  He was still one of the younger players at this level.  But the naysayers didn't like the fact that he struck out 107 times.
Davis moved up to AA in 1998.  Once again, he was one of the younger players at his level, and again he managed to improve his offense.  His batting average, slugging average and on-base percentage rose significantly while he lowered his strikeout rate by nearly 50 percent!  But still that wasn't enough to convince the minor league gurus that this guy was for real.  So when he began the 1999 season at AAA going 1-for-33, the Davis detractors were in full chorus, crowing that they had once again unmasked a suspect posing as a prospect.  I don't know if Davis heard them or not, but he responded.  Since that season-opening slump, Davis has hit .360 with nearly half his hits going for extra bases.  As soon as the Pads trade one of their catchers, Davis will be promoted and become their everyday catcher.
Davis' calling card has always been his defense.  In 3 of his 4 years in the minors, he has thrown out more than 50% of would-be base stealers.  He blocks pitches well and doesn't let his hitting affect his concentration behind the plate.  Many of the experts have comared him to Jim Sundberg, but I think he will be far more potent offensively.  In AA, he produced similar numbers to those of Charles Johnson, but Davis was a full 2 years younger.  My guess is that once he gets settled in, Davis will hit around .275 with 20-25 homer power while completely shutting down the opposition's running game.