Regardless of past success, trying to forecast the performance of any bullpen from one season to the next is difficult. Blame it on the vagaries and fickle nature of the job.
“Health issues, overall workload. People don’t realize it but every time a pitcher stops throwing — reliever, starter, even coaches, players — there’s always a question: I wonder if I will throw as hard as I did last year,” said Red Sox pitching coach Juan Nieves. “There’s always how a bullpen works and there’s also the situation of the game, the days that you have that reliever available for that specific spot, the bounces of the game. But health issues, I think, is the biggest thing.”