Remember the kid in high school who always got straight “A”s? While everybody else was going about their business doing their best to stay afloat, that kid would seek out his or her own challenges just to try to make school interesting. Whether you loved, hated, or were that kid, you’ll never forget the way he or she seemingly operated at another level. In major-league baseball this year, there were a few players worthy of a comparison to that kid, but right now we’re going to talk about the one team who warrants the comparison: the Cubs. Specifically, we’re going to look at one way they challenged themselves and how it might pay off in the playoffs.

How do you improve when you’re already the best? That’s a somewhat obnoxious oversimplification of the situation the Cubs faced prior to the July trade deadline, but it’s not without merit. The Cubs have had ups and downs throughout the season, but it would be disingenuous to attempt to contend that a team ranking atop the majors in wins, team RA9, position-player wRC+, and defense is anything less than the best. They enter the playoffs the easy favorites on paper and, remarkably, that probably would have been true even if the team had failed to make a single upgrade at the trade deadline.

Of course, they didn’t stay quiet in July. As you know, their big splash was the acquisition of Aroldis Chapman – a move which helped shore up their bullpen as well as address their lack of left-handed relief options. Chapman has been predictably great for the Cubs and figures to be an important part of their postseason run, but that’s not the move we need to talk about. The Chapman acquisition is important, but its impact is boringly straightforward. The more intriguing move was the acquisition of another left-handed pitcher: Mike Montgomery.

With the Cubs in need of left-handed arms, Montgomery was the first one they secured prior to the trade deadline, less than a week before Chapman would also be added to the mix. In a world where trade scenarios are hypothesized ad nauseam, this one — as noted by Jeff Sullivan at the time — was a relative surprise. Montgomery was a swingman with five remaining years of team control who was posting solid numbers for the Mariners. That said, his price tag wasn’t negligible, as the Cubs were compelled to send hitting prospect Dan Vogelbach to Seattle in return. (Jordan Pries and Paul Blackburn were also sent to Chicago and Seattle respectively.)

Almost as soon as the trade was made, it became clear that Montgomery filled a crucial need for the team that seemingly had everything. Although the Cubs’ rotation had been stellar — featuring a starting five of Jon Lester, Jake Arrieta, Jason Hammel, John Lackey, and Kyle Hendricks — the lack of depth behind those five was a real vulnerability. It’s seemingly inevitable that at least one starting pitcher will break down in each rotation and, unfortunately for the Cubs, they’ve seen that happen. Lackey hit the disabled list in August with a shoulder injury and Hammel has struggled with ineffectiveness and an elbow injury which may keep him from postseason play.

Since joining the Cubs, Montgomery has pitched 17 games, 12 in relief and five as a starter. Through 38.1 innings, he’s posted a 2.82 ERA, 23.2% strikeout rate and an 11.9% walk rate. The walks are higher than is ideal and the home-run rate (35.7% HR/FB) has been horrid, but that’s picking nits on a sixth starter striking out nearly one-in-four batters!

What Montgomery brings to the table is a mid-90s fastball and secondaries that have gotten tremendous results this season. Opponents have hit for a 53, 10, and -5 wRC+ against his changeup, cutter, and curveball respectively. The curveball in particular has developed into a monster out pitch for Montgomery and it’s one he’s relied on with increasing frequency since joining the Cubs.

Naturally, he’s an imperfect pitcher; you don’t get to be a 27-year-old sophomore swingman by being elite. His fastball gets hit hard, he’s susceptible to getting beat by right-handed batters, and he struggles his second and third times through the order. But the thing about the Cubs is they don’t need to Montgomery to be their best pitcher or even their fifth- or sixth-best pitcher. They need a reliable lefty to bridge gaps as necessary between starting pitchers and the back of the bullpen, whether as a lefty specialist or a multiple-innings arm. It’s a glamourless position — and, frankly, it’s one for which Montgomery is overqualified — but such is the nature of playoff bullpens when rotations shrink and bullpens swell with the excess.

What makes Montgomery particularly indispensable to the Cubs at present, however, is his handedness. If the Cubs face a situation in the NLDS where they need to get through Curtis Granderson and Jay Bruce or Denard Span and Brandon Belt before Aroldis Chapman enters the game, Montgomery’s your guy. But more than that, their potential NLCS foes, the Dodgers, are notably vulnerable to left-handed pitching. Perhaps it’s premature to look ahead at the Dodgers, but it’s hard not to notice the critical role left-handed pitchers could play against a lineup that has quite literally been the worst in the majors against left-handed pitching.

Maybe all of this will go for naught. Perhaps the Cubs starters will be able to go deep enough into games that Montgomery never becomes a critical factor. Or perhaps the rotation will struggle and the high-leverage, middle-inning spot against lefties never arrives. But part of being the best is having the luxury of overpreparation. The Cubs not only have depth, but in Montgomery, they have depth that’s capable of making a real impact. It seems like every October there are surprise heroes from Cody Ross to Edgar Renteria to David Freese. It’s rare that a non-closing relief pitcher gets any glory, but, who knows, maybe Montgomery will be some version of this year’s surprise star. Regardless, the Cubs are better with Montgomery than they were without him and, given the strength of their roster, it seems almost unfair that they found multiple ways to upgrade at the trade deadline.