Martin Perez
The Boston Red Sox signing Martin Perez is a realistic and logical move. Perez is not going to carry a rotation, which is a given. However, he would be a crafty left-hander that would make a great fifth starter.
Perez, who will turn 30 in April, ate innings for Boston in 2020 and has proven to be capable of eating a lot of innings and being durable, having three seasons in which he threw at least 165 innings since 2016. He has pitched for the Rangers, Twins, and Red Sox. Teams are intrigued by pitchers who can stay healthy and toss a bunch of innings at a major league level.
In 2020, he went 3-5 for the Red Sox with a 4.50. That does not seem impressive, but he was their only starter to start double-digit games, starting 12 games. Perez would not be expensive and would want a short-term deal, which would be appealing to Boston.
The Boston Red Sox are going to address their rotation, that is just a given fact. They need pitching and there is plenty on the market. It is just a matter of who they sign, and when they sign them. The free agent market is as slow as molasses and it might be weeks until the dominoes start to fall and free agents find their homes.