For nearly a year, nobody knew if Aaron Hill would ever play baseball again.
The Arizona Diamondbacks' second baseman suffered a concussion in what should have been his breakout campaign in 2008. At age 26, Hill was coming off of a brilliant 2007 season in which he hit .291 with 47 doubles and 17 homers.
But the breakout never came.
Hill collided with teammate David Eckstein on May 29 of that year and missed the rest of the season.
There were times in 2008 when the outlook was pretty grim. Meggie Zahneis of mlb.com interviewed Hill earlier this year and asked him whether he thought he might be done as a baseball player.
I tried not to, but human nature is to put it in the back of your head. There were times I thought I was, because you hear all of the horror stories of guys that were hit and were never able to step on the field again.
Hill returned to hit 36 home runs for Toronto in 2009, but followed that up with a .205 batting average in 2010. He split the 2011 season between Toronto and Arizona, ending the year on a positive note by posting an .878 OPS with the Diamondbacks, albeit in just 33 games after he was traded.
But now, in 2012, Hill is doing the impossible: he's having his best season to date after suffering a severe concussion.
Hill's hit for the cycle twice this year, the first time that's happened since 1931. He's also put up a terrific .298/.353/.502 triple-slash line. If he keeps up his current pace, he'll finish with the highest WAR (currently projected at 4.5 by Fangraphs.com) and OPS of his career.
That's notable because if you go down the list of MLB players who've suffered an injury like Hill's, you'll see a lot of guys who never fully recovered.
Minnesota Twins' first baseman Justin Morneau won the American League MVP in 2006 at age 25. But in 2010, he suffered a concussion that nearly derailed his career. In 2011, Morneau hit just .227 in 69 games. His power deserted him, as he hit just four homers that year.
And this year, Morneau's been slightly better (hitting .276 with 16 home runs), but hasn't come anywhere near returning to his pre-concussion levels.
The Baltimore Orioles' Brian Roberts is another example of the devastating effects of concussions. Roberts' concussion problems started in 2010 and he missed more than a year after suffering another one on May 16, 2011. Ultimately, Roberts has played in just 56 games since his last concussion and hasn't been half the player he was before the injury.
Those are extreme examples of players whose careers took nosedives after their concussions. Some players, depending on the severity of their injuries, have returned to their previous levels (Angel Pagan and David Freese, for example).
But nobody has ever done what Hill's doing. He lost a year to his concussion and is now having the best season of his career. Among second basemen, only New York Yankees' Robinson Cano has accumulated a better WAR than Hill's 4.0 so far this season.
And if the Diamondbacks manage to sneak into the postseason—they're presently five games back in the NL West—Hill will have been largely responsible.
A five-game deficit sounds like an insurmountable obstacle with about 40 games to go. But hey, Aaron Hill's already done the impossible.