Outside of Cobb I can't think of a single great player that Thompson has drafted in the past four years. In his first four drafts TT drafted Rodgers, Collins, Nelson, Jones, Finley, Sutton and Matt Flynn. While some may disagree with Finley's inclusion, try and remember how dominant he was before hurting his knee (that playoff game was INSANE). I didn't include CM3 in that list because I wanted to keep the timeframes similar but you get the point.
Now, the problem that TT presents is that he relies SO heavily on the draft that any decline, if it exists, becomes a pretty big problem. Do I still think Thompson is a good GM? Yeah. Is he perfect? Nope, and I won't ignore his flaws just because he's better than some of the other GMs in the NFL.
Funny thing, the players you mention as being great picks all have one thing in common (except Sitton). They all didn't provide much impact until the 3rd of 4th year.
Jordy Nelson
3rd year 45 Rec 582 yds 2 TDs
4th year 68 Rec 1200 yds 15 TDs
Finley 2nd year
Jones 6th year
Anyway, here are a few players who may still break out (from most to least likely per year):
2010 draft
Quarless - has done okay at times - had the biggest game of his career last week
Bulaga - Our best tackle when healthy, hope he comes back fine
Newhouse - bwhahahaha, just kidding - you can't win em all
Neal - experiment at OLB is better than I expected. Give him till next season to see if it clicks
2011 draft
Randall Cobb - most agree on this
Davon House - I like House and think he will have a good career for the Packers
Derrek Sherrod - If he can overcome the broke leg, it will be interesting to see what he can become
2012 draft
Casey Hayward - serious consideration for defensive rookie of the year, luckily his injury has a high recovery rate
Mike Daniels - looking like a very good DE for us (I think you maybe forgot about him)
Nick Perry - Still adjusting to the pro game
Jerrel Worthy - he hasn't shown me much, but there is still a chance he comes through
2013 draft (way to soon but . . .)
Lacy - probably the steal of the draft so far
Bak - wait, this may be the 2nd steal of the draft
Hyde - no pick surprised me with his impact as much as Micah
Jones - I think he will be special
Boyd/Palmer/Barrington who knows?