I really liked Bronson Arroyo and was a little disappointed when he was traded away. I thought Arroyo had the talent to develop to be a very strong third starter for the Red Sox. This theory has been basically proven since he went to the Cincinnati Reds. I also got the impression that Arroyo really enjoyed being in Boston and never really wanted to leave.
Arroyo was originally picked up on waivers from the Pittsburgh Pirates in 2003, just the kind of short-sightedness that has lead to the team not finishing above .500 for almost two decades. Arroyo did not pitch much in the Majors with the Red Sox in 2003, but put up some decent numbers. In 2004, he was 10-9 with a 4.03 ERA. He also played a role in the postseason that year.
In 2005, Arroyo was one of the better pitchers on the team, going 14-10 with a 4.51 ERA in 205.1 innings.
He signed a team-friendly contract after the year and looked like a durable workhorse for years to come. Then, Theo Epstein in one of his worst trades, dealt Arroyo to the Reds for Wily Mo Pena, a player with a world of talent, but no idea how to grasp it.
Arroyo, of course, has generally pitched well since being traded.