I'm not a fan of this trade for you.
re: Pettitte.
He was old back in 2010... check his month-to-month game log of IP vs. K.
His lowest K/9 months were April & May!!!
He was actually better K/9-wise,
later in the season.
Jim Johnson seems to be clicking on all cylinders... and I honestly think he is the real deal this year. Full confidence. I don't focus on BABIP too much for RPs. I think they typically can have crazy-low (seeming "out-of-whack") BABIP because they can be so
focused for a short time (1 IP).
If you look at a full list (incl. non-qualified RPs), you'll see that most of the lower BABIP are relief pitchers. It's just different, a pitchers "focused" stuff is just harder to hit. Contact may be made, but not good contact. The lower BABIP correlates to the lower WHIP and lower ERA for RPs... IMO.
I'd decline this trade.
I like Gallardo, but I don't see him being a significant upgrade on Pettitte and obviously Jim Johnson is a very good trade chip for you.