twenty team leagues are so difficult to predict, because so much depends on the health of key players. With so few stars on each team, an injury really could hurt. That's why I am a little uncomfrtable with sheets and sabathia as your number one and two starters.
Offensively, I think you will be fine IF chipper can stay healthy. I disagree that Holliday is unproven and I think he and tex will be a great 1-2 punch on offense. I would try to upgrade the OF2 spot and try to grab a reliable second level starter in case sheets goes down (think and barry zito type who you can count on for at least wins and innings). Your main trade bait to fill these holes may be gonzalez.
As for speed, just scour the wire aggressively - in a 20 team league a bunch of teams will be seriously lacking speed. Good strategy on punting saves and grabbing holds.