http://blog.masslive.com/redsoxmonster/2013/03/boston_red_sox_2013_questions.html
Middlebrooks has the strength to hit 30 home runs, that's not the issue. The real question is how often he makes contact, and how solid that contact is.
The 15 home runs are encouraging but here are two other 2012 stats that should cause concern:
Middlebrooks drew only 13 walks and he struck out 70 times. The Red Sox have always stressed the value of drawing walks and not striking out too much. Last season's squad strayed from that formula. The Red Sox were fifth in the American League in strikeouts and ranked 13th in drawing walks.
With the team trying to get back into the habit of striking out less and drawing more walks it isn't out of the question that a player such as Middlebrooks finds himself hitting home runs at a decreasing rate.
Making contact can mean hitting the ball to the opposite field, but that's generally not a great formula for producing a ton of home runs. Middlebrooks also hit 5 of his 15 home runs on the first pitch. Players looking to cut down on strikeouts and work more walks don't swing at the first pitch all that often.