Sans injuries (or being cut)...
C -- Johnny Estrada (31 R, 4 HR, 39 RBI, .261 avg)
1B -- Justin Morneau (66 R, 22 HR, 79 RBI, .239 avg)
2B -- Kaz Matsui (31 R, 3 HR, 24 RBI, .255 avg, 6 SB)
3B -- Adrian Beltre (69 R, 19 HR, 87 RBI, .255 avg, 3 SB)
SS -- Orlando Cabrera (70 R, 8 HR, 57 RBI, .257 avg, 21 SB)
OF -- Corey Patterson (47 R, 13 HR, 34 RBI, .215 avg, 15 SB)
OF -- Carlos Beltran (83 R, 16 HR, 78 RBI, .266 avg, 17 SB)
OF -- Vernon Wells (78 R, 28 HR, 87 RBI, .269 avg, 8 SB)
I would say, based on the hype (in these forums, especially), these were the biggest diappointments. Some guys are obvious, but with the wood everyone sported for Morneau, I thought he should be included. Kaz Matsui was probably drafted in every league, and held on to for the first month after he had another great opening day.
Vernon Wells was hyped up to be Mr. Breakout this year, especially after it was reported that he was going to run more this year. But although he improved slightly over last year, his .269 average (keep in mind he led the AL in hits in '03) and 8 SB left owners scratching their heads.
Oh, and Estrada was easily the biggest bust at catcher this year. He was probably a top-8 catcher coming in, and now he probably won't start next year. His BA dropped over 50 points!