Sometimes, offseason acquisitions work out. Sometimes they don't. Sometimes, they are spectacular failures.
We can talk about this now. Matsuzaka was the subject of the highest posting fee in baseball history to that point. The Red Sox paid $51,111,111.11 just to talk to Matsuzaka about playing for them. They outbid the Rangers, Mets, and Yankees among other teams. Matsuzaka was supposed to be an ace for whoever got him. They then signed him for a $52 million, six-year contract. It was the highest contract anyone ever got coming from Japan.
2007 proved to be a reasonably decent rookie year. Matsuzaka pitched to a 15-12 record with a 4.40 ERA and 201 strikeouts in 204.1 innings. Not bad, but not quite what was expected. He finished fourth in the Rookie of the Year vote and won Game 3 of the World Series. He even helped himself with a two-run single. All in all it was a fairly successful season.
His 2008 season was even better. He won 18 games against just three losses and a 2.90 ERA with 154 strikeouts in 167.2 innings. He finished fourth in the Cy Young race. He did show a tendency to nibble at the corners at the plate and throw a lot of pitches. But nonetheless, his numbers looked great on paper. He looked like he could be the great pitcher the Red Sox thought they were getting.
In 2009 however, the injuries and tendency to throw a lot of pitches started to accumulate. The next four seasons saw his numbers dramatically decline. He pitched in only 56 games over the next four years with a 17-22 record and a 5.53 ERA with 254 strikeouts.
At the end, the injuries and the number of pitches did him in. When he was aggressive, he was good, when he nibbled he had a tendency to get hit hard. The money just was not worth it at the end.