Check out the drafts Vermeil oversaw from 1997-1999. A pile of productive stars and blue collar pros for those Rams teams. Vermeil didn't have the ego that destroyed so many other coaches (see Martz, Mike). He didn't try to get cute, he didn't try to prove he was smarter than everyone else come draft day- he recognized guys that could play football and picked them, and didn't take flyers on potential and glitz. Perhaps more than anything, he understood that the game was won in the trenches.
If Vermeil had stayed on, and been the check on Martz's ego that was needed, those teams would have won at least one, and possibly as many as 2-3 more Super Bowls.