You need to read Jim Baumbach's column on Jorge Posada's return to catching duties. In fact, you may want to frame it. History tells us Posada's days behind the plate are numbered.
Posada will turn 39 in August, an age where starting catchers are severely endangered. And their best years are generally behind them.
Bill Dickey, the Hall of Famer who was the last Yankee to hit grand slam home runs in consecutive games before Posada did it Saturday and Sunday, made his career from 1936 to 1939 when he averaged 25 homers and 115 runs batted in. He started to decline at 33 and was finished at 39.
Yogi Berra was the next catcher to make the Hall as a Yankee and he averaged an astounding 23 homers and 108 RBIs from 1949-58. He went downhill after 34 and was finished as a Yankee at 38.
For all the plaudits that Posada deserves, realize that he has averaged 15 homers and 61 RBIs as he reaches the middle of his 16th season. Thurman Munson averaged 10 and 63 in 11 seasons.