I was looking at both of Clemens' 20k games and he was facing extremely weak lineups, for the most part, both times. Plus, against the Mariners, he gave up a HR and (i think) 4 hits and against the Tigers he gave up 5 hits. That Tigers lineup only had 2 batters OPS over 800 and the Mariners lineup had 3 and nobody batting over .250 at the time (thought it was early in the season.) Interesting note, Brad Ausmus was involved in 2 20k games.