On a frigid afternoon in Denver, Kyle Schwarber wouldn't let a bombardment of sleet ruin what he'd been looking forward to all morning.
Schwarber, the Cubs' third catcher in case of emergency, would be the backstop for that day's bullpen session, in part to maintain receiving repetition, but to also see first-hand what the Cubs like so much about right-hander Tyler Chatwood, whose day it was to throw.
"Being able to get back there and catch him and see what his stuff does and just give him my input if I was hitting here or [discuss] the action of a pitch that we really want, I think that it's really good," Schwarber said. "Because the guy's got all plus stuff."
Since that side session, Chatwood has put together two best starts since signing a three-year, $38 million contract with the Cubs last December, including seven shutout innings in a 2-0 win over the Brewers on Sunday that lowered his ERA to 2.83.
It'd be foolish to correlate one bullpen to immediate and sustained success, but the methodology of having an established hitter like Schwarber catching Chatwood's bullpen is reflective of why the right-hander and the Cubs have formed such a cohesive union, one that could be career-propelling for the 28-year-old.

The Cubs believe Chatwood has a true five-pitch mix, of all plus stuff: a four-seamer he elevates, a two-seamer that moves in on righties, a changeup that effectively coats the white, a cutter he developed after ditching his elbow-straining slider and an off-the-table curveball that some in baseball circles suggest has the potential be elite.
With the physical (and mental) ease of not pitching at Coors Field's high altitude anymore after five seasons in Colorado, Chatwood feels he's in position to fully exploit his repertoire. The stark contrasts of the way his pitches behave at and away from Coors Field may have contributed to drastic home-road splits over his Rockies tenure -- he posted a 5.17 ERA in Colorado and a 3.18 ERA on the road.
"It was tough for me here," Chatwood said two weeks ago in Denver.
"My curveball is a lot sharper than it's been in the past. I have a way better feel for it … My four-seam and two-seam play very well off each other. My two-seam has depth, so I feel like they have to see it up out of my hand. So if I throw a four-seam up, I feel like it's been beating hitters right now, just because it has the carry rather than sink. So I'm able to utilize two different pitches that I've never really used."
Consider this two-seamer to Tommy Pham earlier this year, which Chatwood said offered movement that he hasn't attained before:
Gif: Chatwood K's Pham
And this curve catching Edwin Encarnacion looking:
Gif: Chatwood K's Edwin
"His stuff is cartoonishly good," Cubs manager Joe Maddon said. "Watch the movement on his pitches. It's different. Not many guys get that kind of movement."
Chatwood's curve averages minus-10.3 inches of vertical break, according to FanGraphs -- Clayton Kershaw territory -- and his four-seamer twirls around 2,400 rpm, well above league average, which, coupled with his mid-90s velocity, creates a rising effect that has become particularly useful in an era when hitters are looking to lift more than ever. And Chatwood is now under the guidance of one of the game's established tutors of the elevated fastball: Cubs pitching coach Jim Hickey, who oversaw a throng of such pitchers with Tampa Bay, including Drew Smyly and Jake Odorizzi.

Chatwood's velocity is down a hair, but that hasn't necessarily helped hitters -- they're batting just .207 against his four-seamer, down from .331 last year -- and their lack of success, he says, has helped him better establish his changeup (Schwarber's favorite of Chatwood's pitches), which has yet to be rapped for a hit. And among Chatwood's entire arsenal, when batters are making contact, they haven't been doing so effectively. He's has given up just one homer among 122 batters faced.
Lowest hard-hit rate (exit velocity 95 mph or greater), 2018
Min. 50 batted balls (165 pitchers)

1. Jose Berrios: 19.2%
   
2. Matthew Boyd: 23.0%
   3-T. Tyler Chatwood: 23.3%
   3-T. Jacob deGrom: 23.3%
   
3. Shane Carle: 25.5%
   Because of his diverse mix, the Cubs are encouraging Chatwood to pitch confidently over the plate, which at times has remained a challenge, as it has his entire career. Chatwood's 11.9 percent walk rate since returning from his second Tommy John surgery in 2016 (he also underwent the elbow procedure in high school) is the Majors' highest, and his 18 percent walk rate in '18 is also the highest in MLB.
   "I'd like to see him real comfortable throwing his fastball where he wants it," Hickey said. "He has scattered the ball at times in his past as well, so I mean, we're not getting Picasso out there, but he doesn't need to be either. He's got a sledgehammer. He doesn't need to wield the scalpel."
   What makes Chatwood such a fit with the Cubs -- and he says this as no slight at the Rockies -- is that they reasserted conviction in his arsenal and tailored their scouting to best exploit it. In a slow free-agent market last winter, particularly among starting pitchers, Chatwood was among the first to sign, and at a higher price than some may have envisioned. But Chatwood said he and his agency had multiple offers the day free agency opened, but they selected Chicago because of comfort and fit.
   "The open of free agency, we had so many phone calls and offers the first day. It was eye opening, but we had a big [idea] of where we could kind of already choose and go," Chatwood said. "Obviously I fell into a great situation."