For a while now, it’s seemed like the beginning of the end for the Pittsburgh Pirates’ run toward the post season. In their last 20 games, the Bucs are 7-13. Entering play on Thursday, they are 8.5 games out in the National League Central. But other teams have faltered, too, so the Pirates find themselves just a half game behind the Cardinals for the second wild card spot. Still, the Pirates need to stop the bleeding, and soon.

In last week’s Impact Index, we looked at Wil Nieves of the Diamondbacks and Chase Headley of the Padres who, in two different games, killed the Pirates with huge, late-inning hits. Today’s Impact Index highlights a member of the Pirates who is single-handedly keeping the Pirates afloat down the stretch.

No, not Andrew McCutchen.

Garrett Jones.

Jones splits his time between first base and right field. From a defensive standpoint, he helps more (or rather hurts less) in the outfield, according to most metrics. But his offense been off-the-charts clutch lately, with big hits coming at crucial moments day after day. Not every big hit has led to a Pirates victory, but not for lack of effort by Jones. He’s been that good.

If you’re a regular reader of the Impact Index, you know we talk a lot about Win Probability Added. WPA measures a player’s offensive contributions toward winning the game for his team. In the later innings, with the score close or tied, each batter’s plate appearances takes on added importance; each one — whether defined by success or failure — will significantly impact the team’s chances to win the game.

Through Tuesday’s games, the Top 300 player performances measured by WPA ranged from Joey Votto’s 1.027 on May 13 to Dee Gordon’s .318 on May 2. ¬†Only two players appear five times on that Top 300 list: Mark Teixiera of the Yankees and Garrett Jones. Three of Jones’ Top 300 WPA games have come in the last ten days. That’s the impact he’s had on the Pirates in August.

Jones’ highest WPA of the season (.568) came in Tuesday’s contest between the Pirates and the Padres in San Diego. Jones walked in his first plate appearance and hit a lazy fly ball in his second. His third time up came in the 6th with the Pirates trailing 2-1. With the bases empty and one out, Jones launched a home run over the right field wall, tying the game. Jones flew out again in the 7th inning but had one more opportunity in the top of the 9th. He stepped to the plate with the Pirates down by two runs. Andrew McCutchen was on first base, with two outs. Jones hit a towering home run to left center field, tying the game at 5-5. You can view Jones’ home runs here and here. Go. Watch the homers. We’ll wait for you. Yeah, the Pirates lost the game in the bottom of the 10th when Chase Headley hit his own towering shot over right field wall.

Jones’ next best outing as measured by WPA (.467) came on August 13 at home against the Dodgers. Jones went 4-for4 with two singles and two run-scoring doubles. With the Dodgers clinging to a 5-4 lead in the bottom of the ninth, Neil Walker popped out to end the game with Andrew McCutchen on deck and Jones in the hole.

And then there was Jones’ .438 WPA last Thursday in the Pirates 10-6 victory over the Dodgers at PNC Park. Ho-hum. Just another game with two 3-run home runs, a walk and a ground out. The home runs came early in the game and built the Pirates commanding lead. So Jones’ WPA for this game was lower than in the August 13 and 21 games because he essentially put the game out of reach.

Quite a run for Garrett Jones.

One other Pirates-related note for this week’s Impact Index. It relates to the 19-inning affair the Bucs played against the Cardinals on Sunday. Pittsburgh won that game on the strength of a Pedro Alvarez home run in the top of the 19th. But the game also featured a tremendous amount of failure at the plate. Seven different players — four on the Cardinals and three on the Pirates — recorded negative WPAs that made the Top 300 Worst WPAs of the season so far. Matt Holliday, Daniel Descalso, Rafael Furcal, and David Freese of the Cardinals, and Neil Walker, Jose Tabata, and Michael McKenry of the Pirates went a combined 3-for-43 in the game.