Jacoby Ellsbury fouled a ball off his right foot in early September, leaving him with a compression fracture. It hadn't fully healed three weeks later, but he ignored the pain and rejoined the Red Sox.

Any number of calamities could have befallen him in the five weeks from the date of his decision until the moment the Red Sox won the World Series. He could have fouled a ball off his foot. He could have felt a twinge while reaching deep for his noted speed. Either would have jeopardized not only Boston's chances of a championship but his own prospects of a free-agent payday.

"The reward was worth the risk,'' Ellsbury said Friday, his freshly issued pinstriped jersey resting on his knee.

The Yankees felt the same way, lavishing a seven-year, $153-million deal upon Ellsbury, 30, who has reigned as one of the game's most dynamic players -- when he's been able to remain on the field.

"There are so many different ways he can beat you, whether it's with his power or with his speed or with his glove,'' Yankees manager Joe Girardi said as Ellsbury was introduced Friday at Yankee Stadium. "Jacoby, you are going to make my job so much easier. You are no longer a thorn in my side; you are a flower in our clubhouse.''

"It was a very easy decision once I started talking to New York,'' said Ellsbury, who was courted aggressively by the Yankees, thanks to stalled talks with Robinson Cano. "They made it very clear that they really wanted me. From there, it was pretty fast.''

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Ellsbury reached out to Derek Jeter and Mark Teixeira with questions about the city and the organization. He came away feeling reassured.

"The biggest thing I've always enjoyed is the expectation of winning,'' said Ellsbury, who will wear No. 22. "And yeah, you have that in Boston, you have that in New York, and the fans expect you to win. That drives me to push my game and compete at a high level each and every night. I enjoy that.''

But that drive sometimes has led to trouble.

Red flags pop up all over Ellsbury's injury history. A collision with Adrian Beltre left him with four broken ribs in 2010. In 2012, Ellsbury separated his right shoulder while trying to break up a double play at second base.

Though general manager Brian Cashman stopped short of dismissing the injuries, the Yankees labeled them as freak occurrences. And ultimately, they pushed forward, attracted by Ellsbury's ability to change games with his bat, legs and glove.

"I've seen him get base hits, I've seen him hit home runs, I've seen him steal second, I've seen him steal third,'' Girardi said. "I even had the pleasure of watching him steal home against Andy Pettitte when I was standing right behind him and we were all screaming at Andy.''

Ellsbury flashed that versatility in the 2013 postseason, hitting .344 in 16 games, and though he didn't homer, he added some pop with four doubles and a triple. He swiped seven bases and was caught only once.

Doing all that despite pain in his foot proved he is "mentally tough,'' Yankees managing general partner Hal Steinbrenner said. He labeled Ellsbury's previous injuries as "freakish.''

"I'd be more concerned if it was a serious shoulder issue that was chronic or serious,'' Steinbrenner said. "I think he'll be fine.''