I'm assuming the reports of Lackey not being happy with the contract situation are true tbf. If he was happy to stay, or, they could work out a new fair contract then that was obviously the step to take. We've seen some baffling decisions in recent years but I can't believe they were willing to trade him if either of those options were available. There seemed like a beef there.
So if that was the case, I don't hate the trade(as in what they were thinking). Take away his disaster both in form and injury in 2014, Craig was batting .312 over 1296 at bats from 2011-13. Get him healthy and back anywhere near that and it becomes a great trade(Edit - great is going too far. A good trade). I think tacking on Kelly was an extra they really wanted as they hoped they might be able to make something happen with a guy who had a great arm.
It's clearly been a disaster, and it's sometimes very hard to look past hindsight while viewing these things, but when it happened I was excited, while being pretty disappointed we were losing such a good pitcher.