The Cleveland Indians bullpen has been incredible since acquiring Andrew Miller

While the Cleveland Indians offense and pitching have gone through slumps in the past month, one constant has held the team in games they probably should have lost: the bullpen.

The Indians reliever core was once thought to be the Tribe's weak link, maybe even the worst individual aspect of the team, but ever since Chris Antonetti shipped a treasure trove worth of prospects to the New York Yankees for Andrew Miller, things have turned around considerably.

It has been just a shade over 30 days since the Indians acquired their star reliever, which means it’s easier to sort the numbers on FanGraphs the perfect time to delve into just how this team’s bullpen has performed since his arrival.

One of the American League’s best since August 1

As a unit, over the last 30 days, the Tribe bullpen ranks third in FanGraphs WAR (1.4), fourth in earned run average (2.78), and fifth in fielding independent pitching (3.20). The kind of teams they trail in these categories are the likes of the Kansas City Royals, who always have a dominant pen, and the Toronto Blue Jays, who have probably the best overall staff in the American League.

With the way the Indians starting pitching has struggled in the last month, only one other AL team, the Minnesota Twins, have had their relievers log more innings than the 100.1 thrown by the Indians bullpen.

This new-look bullpen has gone a long way towards reversing the damage done in the first half of the season; they rank sixth in fWAR (3.4), second in ERA (3.36), and fourth in FIP (3.71) on the season.

The impact of Andrew Miller is undeniable

Any discussion about this bullpen over the last 30 days has to begin with Andrew Miller. Terry Francona has continued to use his shiny new toy in high-leverage situations, or with the better parts of lineups coming up to bat. As a result, he has the third-highest WPA since joining the Indians at 1.21.

Opposing batters frequently look lost against Miller. Since joining the Tribe, they are making contact 61.1 percent of the time, and swinging and missing 19.2 percent of the time. For a micro look at this, just bask in how silly Andrew Miller makes his victims look when they try to hit his disgusting slider:

That. Is. Not. Fair.

Khris Davis, a grown man, falls like a wobbly toddler still unsure how to balance his upper-body, while Brian Dozier, also a grown man, looks like he regrets every decision in his life that led to this moment.

"Why did I join Little League?"

The sample size is minuscule, but over the same 30 days, Miller’s devastating slider is third-best among AL relievers (3.4 weighted value) behind only Ken Giles’ and Edwin Diaz’s own sliders.

Everyone else has been pretty good too

Miller is the most valuable Indians reliever in terms of FanGraphs WAR over the past 30 days at 0.5, but the next closest is a bit of a surprise. For all the ire he attracted in the fist half of the season (and in previous seasons), Zach McAllister has had a rejuvenation since Miller joined the fray.

The 28-year-old starter-turned-reliever has a 1.84 ERA and a 2.46 FIP over 14.2 innings this past month — tied for the second-most IP with Andrew Miller, behind only Dan Otero.

Prior to August 1, McAllister has 27.1 innings under his belt in 2016 with a 5.27 ERA and 4.90 FIP. He was getting hammered, giving up 1.32 home runs per nine innings, and struggled with walks. Again, the sample size is small, but since August 1, all those issues are seemingly gone.

McAllister importance, or maybe just the trust that Francona still has in him, was on display Monday night when he was called upon to get one batter out with the bases loaded. He did just that.

Saying that Dan Otero has benefitted from Miller might not be true. Otero has just been phenomenal for the Tribe all season long. He leads all Indians relievers with a 1.1 fWAR, allowing just eight runs in 57.2 innings. He has been great in the post-Miller month, of course, but Otero has been a godsend for this bullpen, even in its roughest moments.

Heck, even catcher Chris Gimenez has pitched a shutout inning this month. Everyone has been great.

The true value of the Miller trade will be determined in the playoffs

I believe I said it on the podcast shortly after the trade, and I still believe it now: The Indians traded for Andrew Miller for one shutdown inning. One reliever is not going to make or break your chances of making it to a playoff game, but having the best bullpen arm in the game could be the deciding factor in winning a playoff game.

If it comes down it, in the last inning of the last game of a series, we will really know if the Indians got their money’s worth in the Miller deal. Right or wrong, if Miller blows a lead in Game 7 of the ALCS, not a lot of people will care that he was lights out for a couple months down the stretch, or that he could be for two more years in Cleveland.

But, no matter what happens then, we can all breathe a little easier now knowing one of the Tribe's biggest flaws has been sufficiently corrected.