I'd take Patterson, has a K/9 of 8.4, WHIP of 1.20 last year. Sure only got 9 wins, but as long as you don't hope for more than 12-13, should be a good later round pick.
Webb seems to be a popular sleeper candidate (especially here at the cafe). His WHIP was at 1.26 last season and struck out 170. I'd probably choose Patterson over Webb, but I'd still worry about the health of both pitchers. While Webb has never been injured (to my knowledge) he's thrown about 600 innings the last 3 years... could be trouble for a 26 year old.
...Boston papers now and then suffer a sharp flurry of arithmetic on this score; indeed, for Williams to have distributed all his hits so they did nobody else any good would constitute a feat of placement unparalleled in the annals of selfishness. -Updike