The Red Sox have ridden a center-field roller coaster with Ellsbury, who managed to play in only 18 games due to injury in 2010, finished second in the AL Most Valuable Player voting in 2011 and fell back to a .682 OPS (on-base plus slugging percentage) in 74 injury-plagued contests last season. In those same three years, Berkman went from a career-low .781 OPS to an All-Star nod and World Series title to a 32-game slog through multiple knee surgeries.
At age 37, Berkman will step into a designated-hitter gig after his home-state Rangers lured him away from retirement. His ailing right knee has improved, and he feels his bat can make an impact after he posted a .259/.381/.444 line in 97 plate appearances last season, his second with the Cardinals.
"We'll find out," Berkman said after signing a one-year deal early this month. "I'm not ancient, but I'm certainly older for a ballplayer. It's not unprecedented for guys my age to be extremely productive. I still feel like I can do that, and we'll find out if that's the case or not."
The myriad other candidates for bounce-back seasons all face their particular challenges but fit into a few main categories.
For the handful of players coming off seasons lost entirely to injury, bouncing back could mean simply returning to the field -- not that they aren't setting their sights higher. The Tigers are counting on designated hitter Victor Martinez to be a key cog in their lineup, the Cubs likely will make Scott Baker part of their rotation and the Angels figure to give Ryan Madson the first crack at their closer role.
The 32-year-old right-hander was slated to close for the Reds last season but underwent Tommy John surgery before throwing a single pitch. With an incentive-laden one-year deal in hand, Madson doesn't want to ease back into action.
"I'd rather hit the gate running as much as I can," he said in December.
Dodgers outfielder Carl Crawford didn't miss last season completely but did have two surgeries -- including Tommy John -- and played in only 31 games for Boston following a disappointing 2011. The Red Sox shipped him to the Dodgers as part of last August's blockbuster trade, and the 31-year-old four-time All-Star is expected to be Los Angeles' Opening Day left fielder.
"Once I start playing like I normally play, I won't be the forgotten guy," Crawford said in October. "I definitely have a lot of baseball left in me. It's good to get a second chance."
Others: Jose Bautista, Chris Carpenter, John Danks, Brett Gardner, Ryan Howard, Matt Kemp, Evan Longoria, Mariano Rivera, Troy Tulowitzki, Chase Utley, Jayson Werth, Brian Wilson.
Major League pitching is a cruel foe, and for young hitters, progress can be fleeting. A promising rookie year can devolve easily into a sophomore slump, setting up the third season as a significant test of viability.
Royals first baseman Eric Hosmer, a former top prospect, now faces that challenge at age 23. Last year he played almost every day but saw his batting average decline from .293 to .232, his OPS from .799 to .663 and his home run total from 19 to 14. He also suffered from some bad fortune, with one of the league's lowest averages on balls in play.
"It's a game of adjustments and you've got to constantly adjust," Hosmer said earlier this month. "The pitcher has a game plan, and we have a game plan going in there. It's just who can adjust more and on the fly, taking each at-bat by each at-bat. It's part of the game. This game teaches you a lot of things, and I just used it as a learning experience and as motivation in the offseason to work hard and come back for a strong year."
Others: Dustin Ackley, Jesus Montero, Jemile Weeks.
For all of the struggles young players go through, experience doesn't provide an antidote to slumps. Plenty of established stars find themselves on the rebound from a tough 2012.
Giants pitcher Tim Lincecum isn't getting past an injury, but he will have to re-establish himself as a top-of-the rotation hurler. The 28-year-old two-time Cy Young Award winner dealt with diminished velocity and a skyrocketing walk rate in 2012, and his 5.18 ERA relegated him mostly to relief work in the playoffs.
But even for those who stayed on the field for most or all of the season, injuries often played some part. Braves catcher Brian McCann logged 121 games despite a shoulder injury that required offseason surgery, but his .698 OPS was nearly 150 points below his career mark before last season. He is targeting an Opening Day return as he enters the final year of his contract with a lot to prove.
"It's just made me want it that much more," McCann said earlier this month. "Sometimes I think you need to hit rock bottom to take two steps forward. I'm hoping that is the case. I've been working really hard this offseason to make sure I get better as a baseball player."
Others: John Axford, Heath Bell, Roy Halladay, Adrian Gonzalez, Tommy Hanson, Dan Haren, Ubaldo Jimenez, Jon Lester, Justin Morneau, Hanley Ramirez, Ricky Romero, Justin Upton, Shane Victorino.