BALTIMORE — You’ve heard of trickle-down economics?
If only it worked as well as the trickle-down effect of Koji Uehara.
When the 41-year-old reliever went down with a pectoral strain, the Red Sox bullpen became a landmine. There was chaos, relievers assuming roles they weren’t used to, and the pen became the weak spot of the team.
There was some reason to believe Uehara would not recover in time to rejoin the team this season, but he did. And since Sept. 1, the Sox bullpen has been the best in baseball. Now there’s a flow, from closer Craig Kimbrel to Uehara in setup to Brad Ziegler as the swingman to Robbie Ross Jr. in high-leverage lefthanded situations. Newcomer Robby Scott has even proven to be a strong multi-inning reliever. And Joe Kelly can be used late in games when a strikeout is needed.
Advertisement
This bullpen order is all because Uehara can hold the fort in the critical eighth inning. It’s made such a world of difference. Uehara’s reemergence is like discovering money in your pocket.
Manager John Farrell was asked if he thought it would be that hard to replace Uehara when he went down on July 19, and he said, “No. I felt like we had candidates here, and I still feel like we had candidates here that I feel could do that. And then we ran up against teams that weren’t great matchups for Brad where we could take advantage of his strengths. We weren’t in the division as much as we are now, where we have heavily laden righthanded lineups. What Koji has done is allow us to match up through the seventh inning and then turn it over to him.”
Uehara may have revived his career by coming back. Now he has a late-season body of work to take into free agency, and the Red Sox certainly have to consider re-signing him.
Advertisement
It seems Farrell again has total faith in him.
“Take away the age and stuff and raw stuff, you’re looking at the most comfortable inning on the field when he’s on the mound, and that’s the way he’s pitched a majority of the time he’s been with us,” said Farrell. “Add to that the quality arms we’ve been able to add in September. Now you’ve added additional arms and that’s why guys are pitching as effectively as they are.”
Entering Wednesday night’s 5-1 win over the Orioles, in which the bullpen pitched two scoreless innings, since Sept. 1 the Red Sox had the lowest bullpen ERA in the majors at 0.89, allowing eight runs (five earned) in 50⅓ innings. The bullpen WHIP was 1.03, fourth in the majors behind the Cubs (0.84), Astros (1.00), and Brewers (1.02).

The Sox’ bullpen had the second-highest strikeout rate per nine innings at 10.91 since the beginning of the month. Only the Dodgers’ (11.90) was higher.
Sox relievers entered Wednesday having pitched 50⅓ innings in September, the fewest in the majors. By contrast, Pirates relievers had thrown 80⅔ innings. For the month, the bullpens with the lowest batting averages against in the majors belonged to the Cubs (.152), Astros (.186), Dodgers (.193), and Red Sox (.193), with Boston having the lowest slugging percentage against at .271.
Entering Wednesday, six teams had not blown a save since Sept. 1: the Red Sox, Indians, Cubs, Orioles, Mariners, and Cardinals.
Advertisement
This month, Kelly entered Wednesday having pitched 7⅔ scoreless innings, Uehara 7, Matt Barnes 4⅓ , and Ross 3. And Kimbrel had gone 4⅓ innings and allowed one unearned run.
Kimbrel had allowed a .071 batting average in 18 batters with nine strikeouts. Kelly had allowed a .207 average with 32 batters faced with 11 strikeouts. And Uehara had allowed a .174 average in 23 batters faced with eight strikeouts.
The Red Sox bullpen is fun to watch again. At playoff time, it can make or break a team.
Red Sox relievers have improved so much that Farrell and his staff will have a difficult time trying to figure out who gets left off the playoff roster.
The configuration is dependent, in part, on the starting rotation. Right now the rotation looks like Rick Porcello, David Price, Eduardo Rodriguez, and Clay Buchholz, with Drew Pomeranz on the outs. Pomeranz would either be part of the bullpen or left off the postseason roster.
Clearly part of the bullpen for the playoffs are Kimbrel, Uehara, Ziegler, Ross, Barnes, and Kelly. Fernando Abad, Scott, Heath Hembree, and Junichi Tazawa are competing for one or two spots.
The Red Sox are also waiting on whether Steven Wright can work his way back to health and on the roster. Wright is on an accelerated throwing program in Fort Myers, Fla. If he shows progress, Farrell may consider carrying him as a starter.
The Red Sox have had to mix and match all season. It started when they lost Carson Smith to Tommy John surgery in spring training. The bullpen was a weakness until Uehara came back and solidified it. He restored order, and heading into the playoffs there isn’t anything better than a stable bullpen.
Advertisement
Nick Cafardo can be reached at cafardo@globe.com.