Second baseman Neil Walker will not play the rest of this season because of a herniated disc, the cause of lower back pain that has troubled him for a month.
Walker will visit back specialists next week.
"He's continually tried to find his way on the field," Pirates manager Clint Hurdle said. "Our training staff has continued to work with him. At the end of the day, I think we got to a very real part of, in Neil's mind, risk versus reward."
Walker missed 15 games from late August to mid-September because of lower back pain. He said in early September that his back tightened Aug. 27. Walker slowly worked his way back, first fielding and running, then swinging, and returned to the field Sept. 14 to pinch-hit.
He started consecutive games on Sept. 15-16, but did not start two games in a row after that. His most recent game played was Sept. 24.
"He wants to be a tough guy and he knows there's times when he's got to play through pain and injury," Hurdle said. "This particular situation and incident and injury has given him perspective to handle accordingly."
Walker, 27, will finish hitting .280 with a .342 on-base percentage and a .426 slugging percentage. He hit 14 home runs and 27 doubles in 530 plate appearances in 129 games.
Walker previously experienced back pain in early July 2011 in Toronto, which worsened after playing on the turf at Rogers Centre.
Hurdle said he would play Jordy Mercer, Brock Holt and Josh Harrison at second base in Walker's absence. Harrison and Holt had split time while Walker was out; Mercer started Friday at second.
Herniated discs, which occur when the tissue between the vertebrae becomes damaged, affect the lower back most often. Rest and exercise can treat the issue, as most herniated discs heal themselves, and only rarely does the case require surgery.
Walker has said he worked on strengthening the muscles in his core to prevent the issue from worsening. The continued attempts to swing and play games provided extra wear on the disc.
Walker is eligible for salary arbitration for the first time this offseason as a Super 2 player. Fangraphs.com rated Walker as worth 3.5 wins above a replacement-level player, tied for the sixth-best mark among major league second basemen.
The only other time Travis Snider robbed a batter of a home run, he did so in Fenway Park in Boston, where the right-field wall is about waist-high.
His efforts Thursday at Citi Field had no such caveat.
"If you watch, I actually got up there a little early," Snider said of his catch above an8-foot-high outfield wall. "I was lucky that I was in the right spot."
The ball fell straight, Snider said, rather than tailing in one direction or another, a key factor in allowing him to catch it.
The catch rivaled those of the Toronto Blue Jays' Rajai Davis, who scaled the left-field wall in Rogers Centre, and the Los Angeles Angels' Mike Trout, who made a running, leaping grab over the wall at Camden Yards in Baltimore.
"The fact that [Davis] was able to get up that wall with the padding is incredible," said Snider, a former Blue Jays player. "I've tried that a few times and been very unsuccessful."