The issues stemmed from a few things. An MRI exam in October revealed a slight tear in League's right rotator cuff, which prompted the Jays to suggest he take some extra time off. During an extended layoff from throwing, League continued to lift weights, which led to an "over-developed lat muscle," as the club initially described the injury.
"I think I did a little too much," said League, who posted a 3.32 ERA over 18 Minor League games this season. "The MRI showed stuff in the shoulder. The lat is connected to the shoulder and when you tighten the shoulder, it's going to pull other muscles that are connected to it."
The problem also affected League's arm angle during his delivery, which has been a continued issue over the past few seasons. When the problem crept up in the spring, the Jays didn't rule out surgery and set a tentative deadline for exploring that option, giving League time to hopefully show progress.
An operation was taken out of the picture when the 24-year-old right-hander started to consistently repeat improved mechanics in his Minor League rehab outings, and when League's fastball returned to the 93-95 mph range. The velocity isn't completely back, but that's not League's focus.
"My goal is to just have similar mechanics to what I had last year," said League, who throws a slider, sinker and splitter. "And to produce the same sinking action on my fastball to get ground balls and get outs. That's the ultimate goal."
That's the focus League has to have, considering he doesn't have the luxury of a 100-mph fastball anymore. For now, the Blue Jays will likely place League into a middle relief role until he shows he's capable of returning to the setup job, which has been filled for most of the year by Casey Janssen.
On the run: On Saturday night, the Red Sox successfully converted a double steal with Jays left-hander Brian Tallet on the mound. It is the latest example of Toronto's inability to keep the opposition's running game in check this season.
Through 90 games, the Blue Jays have yielded an American League-high 84 stolen bases, and the club's catchers owned an 11 percent caught-stealing average, which is the lowest in the big leagues. The Major League average for caught-stealing percentage is 26.
If veteran Sal Fasano, who threw out runners roughly 21 percent of the time earlier this year for the Jays, is taken out of the mix, catchers Gregg Zaun and Jason Phillips have combined for just a nine percent caught-stealing percentage.
"That's how teams try to exploit us," Toronto manager John Gibbons said. "That's all I have to say."
On second thought: A day after praising Vernon Wells' discipline as Toronto's leadoff hitter, Gibbons moved the center fielder back into the No. 3 spot of the lineup. Now that Wells has started to emerge from his persistent slump, Gibbons wants to provide him with more run-scoring opportunities.
"Maybe this way he can get him a few more RBIs," said Gibbons, offering a brief explanation for the sudden switch.
Actually, Wells averaged an RBI every 4.3 at-bats in 16 games as Toronto's leadoff man, compared to one every 9 at-bats in 55 starts as the No. 3 hitter, entering Sunday. When batting first, Wells has hit .304 (21-for-69) with seven homers and 16 RBIs. He's batted .230 (50-for-217) with five home runs and 24 RBIs in the third spot.
On the bench: For the first time this season, Toronto's Frank Thomas was not in the starting lineup in a game where the designated hitter was available. Prior to Sunday's tilt in Boston, Thomas had started 81 games as a DH and only sat nine times -- each during road contests versus National League foes. Matt Stairs started as Toronto's DH on Sunday.
Did you know? Entering Sunday, Jays second baseman Aaron Hill has hit .500 (8-for-16) with one home run and four RBIs in his last four games. In the 11 previous contests, he posted a .150 (6-for-40) average with no homers and three RBIs.
Quotable: "I've got no answers for you. It is what it is." --Gibbons, when asked about his catchers' low caught-stealing percentage
Coming up: Toronto right-hander Josh Towers (4-5, 5.07 ERA) is slated to take the mound in the opener of a four-game set against New York at 7:05 p.m. ET on Monday at Yankee Stadium. The Yankees will counter with left-hander Kei Igawa (2-2, 7.14 ERA).