Ryan, speaking on KESN-FM, Dallas, said Hamilton's "timing on quitting smokeless tobacco couldn't have been worse" as the Rangers faltered down the stretch of the regular season, costing them an American League West title.
After losing the crown to the Oakland Athletics on the last day of the season, the Rangers were eliminated in a one-game wild-card playoff against the Baltimore Orioles.
Hamilton, who ended up hitting .285 with 128 RBI and 43 home runs for the season, went 0-for-4 against the Orioles and committed a key error in the final game against the A's.
Ryan said Hamilton's decision to give up chewing tobacco in midseason was linked to his performance later in the year, saying it had a "drastic" effect on the outfielder.
"You would've liked to have thought that if he was going to do that that he would've done it in the offseason or waited until this offseason to do it," he said.