I did like him as a broadcaster when he started, then of course hated him during the fierce Red Sox vs Yankee rivalries of the mid 2000's. His complaining about Jason Varitek's "gloving" A-Rod in the face was hilarious. And he did lose his fastball towards the end, as do all of us. But in the big picture those are minor quibbles, and agree he was very insightful in discussing the strategies and possibilities along with the various strengths and weaknesses of players.
Was signed by the Red Sox after Carlton Fisk hurt his knee in 1974. The Sox catching corps consisted of Bob Montgomery and Tim Blackwell, so it was hoped his experience would help in the stretch run in which the Red Sox started September 3 games up in first place. Unfortunately, he wasn't nearly enough as the Sox would go 11-18 in the month and finish in 3rd place, 7 games behind the Orioles. He had a nice 2 game stretch in 1975 where he went 4 for 8 with a double and triple, which basically led to his 166 OPS+ in those 22 at bats. But he was soon after released in order to make room for Fisk, who came off the DL after recovering from a broken hand he received in spring training after being hit by a pitch. Probably a mistake to cut him instead of Bob Montgomery. McCarver would go on to have some decent years in Philly, and his 99 OPS+ in 90 games in 1978 may have helped the Sox spell Fisk here and there. But Zimmer probably would have put him in the dog house for some reason.