Hi everybody. It's been a while since I've checked in, but I have a question that I'm hoping you can all help me out with. I'm in a keeper league where we keep 12 players. There are no contracts or anything like that, and nearly every offensive stat counts, including:
R, H , 2B , 3B , HR, RBI, SB, BB, K, AVG, OBP, SLG

I have an insanely good 1st place team right now, and the following players are at least possible keepers for next year (I'm leaving out my pitchers because they're irrelevant for this question:
Napoli
Votto
Beltre
Kendrick
Kemp
Heyward
Zobrist
Gardner
Morse

Long story short, I've been offered Carl Crawford for Brett Gardner. I'm in first place right now, and believe that I can stay at or near the top into the playoffs. I'm not worried about who can help me over the next couple months - I'm more looking to get help for this year's playoffs and next year's season. Should I accept the trade to get Crawford, or hang onto Gardner. Both players serve as my LF, so position doesn't matter. Thoughts?