In 2010, I always argued strongly that Lackey's campaign was extremely underrated. The ERA was a bit high at 4.40, but 215 IP and 21 QS was extremely valuable, especially in a year when the team's 7th inning reliever was Scott Atchison, and the offseason was the best in the league and good enough to get him some support. Fangraphs says he was worth 4 wins and 16 million. Maybe not quite, but I'd argue he gets a pass for that year --especially considering the uneven first/second half year splits
2011 was an epic disaster for everyone, Lackey included.
2012 was a lost year for Lackey because of TJS. But it unlocked the low cost 6th year option, and the team knew about the TJS early enough in 2011 that they could have replaced his production in the offseason. Instead they went with Aaron Cook and Padilla. The Red Sox built in flexibility to the contract because they were concerned about his elbow. I just don't think you can say the contract is bad for something that the team's medical team knew about, and factored into their long term plans as a contingency.
In 2013, he was the most reliable arm in a rotation that eventually won a World Series. In April, 2.61 ERA, May 3.06, June 3.03, July, 3.67, August, 3.09, September 4.98, October 2.77. The only time he pitched poorly was when it didn't matter.