The chill in the air. The changing colors of the leaves. The earlier sunsets. So much to look forward to as the calendar turns from summer to autumn. Except, of course, for the dwindling days of the baseball season. Those are no cause for celebration, but instead bring the anguish of a long baseball-less winter.

But do not despair, baseball friends. Let us rejoice in the season nearly completed. And let us honor the great men who rose from the dugout bench, night after night, to enter a game in progress and make it their own. The pinch hitters. The middle relievers. The heroes of the Impact Index.

That’s right, it’s time to hand out the awards for the most Impact Index-y hitter and the most Impact Index-y pitcher of the 2012 season.

Let’s start with the Impact Index Pitcher of the Year.

We’re all familiar with the Baltimore Orioles’ outstanding record in extra-inning games. The O’s lost their first two extra-inning games of the season on consecutive nights, both to the New York Yankees. That was on April 10 and 11. Since then the O’s have rattled off 16 consecutive extra-inning victories. I think those have something to do with the Orioles 88-66 record heading into Tuesday night’s action, despite being outscored 683-676.

Someone had to pitch — and pitch well — for the O’s in all those high-leverage situations. Actually, several someones. One pitcher in particular stands out. Right-handed reliever Darren O’Day.

The O’Day is in his first season with Baltimore after spending the better part of 2009 and all of 2010 and 2011 with the Texas Rangers. He’s appeared in 66 games so far for the O’s and has complied a 7-1 record with a 2.35 ERA. He’s struck out 9.3 batters every 9 innings, against only 1.9 walks, for a very effective 4.79 strikeout-to-walk ratio. In fact, O’Day has the 8th-best K/BB among American League relievers, and the 4th-best among non-closers.

O’Day pitched in extra innings in four of the Orioles 18 extra-inning games. In three of those appearances, O’Day achieved a Win Probability Added at .277 or higher. Each of those performances is in the top 125 WPA scores by a reliever in the majors this season. That’s out of a total of 13,611 reliever appearances so far in 2012. O’Day added a fourth top-125 WPA score in a non-extra inning game, giving him the most top-125 WPA performances by a non-closer reliever.

Perhaps O’Day’s best performance this season, though, came when Orioles manager Buck Showalter and closer Jim Johnson set up a prank on O’Day, who is famous for riding a Solowheel around the clubhouse. Take a look.

The Impact Index Pinch Hitter of the Year plays just down the road from O’Day: Chad Tracy of the Washington Nationals.

Heading into Tuesday’s games, there had been 5,146 pinch hit appearances this season. The highest game WPA for a pinch hitter belongs to Raul Ibanez of the New York Yankees. He scored an .869 on Saturday when he hit a pinch-hit home run in the 5th inning against the Oakland A’s to give the Yankees a 5-4 lead and then stayed in the game for three more plate appearances: a hit by pitch, a double, and a game-tying home run in the bottom of the 13th, after the A’s had taken a 9-5 lead in the top of the inning.

Tracy hasn’t had a game quite like Ibanez’s but that’s because he typically comes out of the game after pinch hitting. Ibanez’s .869 WPA came from four plate appearances. But Tracy did record the 13th-highest WPA in a single pinch hit plate appearance — a .429 on April 7. With the bases loaded and two outs, and the Nationals trailing the Chicago Cubs 4-3, Tracy came to the plate to face Cubs closer Carlos Marmol. Here’s what happened:

Washington went on to win that game 7-to-4.

Including that pinch-hit single on April 7, Tracy has 10 of the top-525 WPAs for pinch hit appearances this season. more than any other player. In four of Tracy’s pinch hit appearances, he whacked the game-winning hit. In one, he slugged a game-tying home run. In all, the Nationals won six and lost four of Tracy’s top-525 pinch hit appearances by WPA this season.

Congratulations to Darren O’Day and Chad Tracy. Our Impact Index Players of the Year.