I don't think much talking needs to be done besides looking at the stats:
WELLS:
WHIP - ERA - YEAR
1.37 - 4.42 - 2006
1.31 - 4.45 - 2005
1.14 - 3.37 - 2004
CLEMENS:
0.53 - 2.30 - 2006
1.01 - 1.87 - 2005
1.21 - 2.92 - 2004
Wells has been a #2 or #3 guy, and isn't even in the same ballpark as Clemens. His WHIP has increased every year, despite pitching in the NL in 2004, AL in 2005 and then (briefly) in the NL again for 2006. His injury-prone back and legs have already been mentioned. Clemens has just been off the charts recently, although his WHIP in 2006 probably would have been higher had he pitched an entire season. Still, Clemens proved in 2005 and 2006 that he is still capable of absolutely dominating the NL, I see no reason why he won't have sucess (albiet not as remarkable as with Houston) if he chooses to go to the Yankees.
Oh, and Wells in for the HOF? Are you kidding?