I watched plenty of Blue Jay games. Delgado cant get grounder's and throws that come to him that a good 1st base player can get. So every game he might not let in a few runs per say, but he lets those tough balls go by and also lets easy ones go by too, which is pretty small, but in baseball, its the small things that count.
So because of Delgado, the guy gets on first, then somebody else hits, he goes to second or third, and know he is in scoring position because of Delgado's bad play. Unlike most good defensive players, he does on a regular basis.
He is an awesome hitter, but is horrible at defence which is key in the National League.
Slammin Sammy is going to the O's.
http://sports.espn.go.com/mlb/news/story?id=1978241
Also, a underrated move was the Mets getting Mientkiewicz from the Bo Sox. While he certainty isn't the hitter Delgado is, Mientkiewicz will really help the Mets horrendous infield defense which IMO is more important than getting another big bat.