MESA, Ariz. -- Mike Montgomery spent all of Spring Training last year preparing to be a starter. Then, when the rotation situation warranted moving the lefty to the bullpen, he pitched in each of the Cubs' first three games of the season on the road in Miami.

"At that point," Montgomery said, "I knew it was going to be that kind of year."

It will be that kind of year again in 2019, and not only for Montgomery. Given that there is no room in the rotation inn right now, both Montgomery and Tyler Chatwood project to start the season in the bullpen. That became even clearer during Chicago's 7-1 victory over the D-backs on Saturday, when both pitchers came out of the bullpen on three days' rest.

Both Montgomery and Chatwood identify as starters, but the Cubs have Jon Lester, Cole Hamels, Yu Darvish, Kyle Hendricks and Jose Quintana locked into the rotation. Since Montgomery and Chatwood are No. 6 and No. 7, respectively, on the rotation depth chart, they will have to remain at the ready as insurance starters, while balancing relief roles.

A handful of other teams around baseball also take that approach -- having the next-man-up in the bullpen rather than working regularly at Triple-A -- but it is a challenging balancing act for both the club and pitchers involved.

"It's a tough role. It's definitely a tough role," Hendricks said. "Being a starter, you have a routine. And then, as a reliever, I guess you can find a routine. But, kind of mixing both of them, going back and forth, it's really hard to settle into one aspect of it. I know Montgomery's done it for a couple years now, so he's probably used to it a little more.

"But, for Chatty, I think he's always started and been on that five-day rotation. It'd be interesting to see where he's at, what they do with him, but how you bounce back and how you get in a routine can be tough."

An important test for Chatwood arrived on Saturday at Salt River Fields.

In the fourth inning, when Hendricks slipped into a one-out situation with runners on first and second, the Cubs summoned Chatwood from the bullpen. He had logged two other relief appearances this spring, but this marked his first time entering with inherited runners.

"You can't have clean innings all the time," Cubs pitching coach Tommy Hottovy said. "So, we're trying to start simulating some more game-type situations for everybody."

Chatwood, who is in the position he is in largely due to the command issues (95 walks in 103 2/3 innings) he experienced last season, generated a pair of flyouts to right field to escape unscathed. The righty followed that up with a clean fifth inning, in which he struck out one and created two groundouts.

"We're all pulling for him," Hendricks said. "It was really good for him to come into this one and get really quick outs. He looked really good."

As Hendricks noted, Montgomery has learned some of the ins and outs of the swingman job.

Last season, the left-hander piled up 124 innings with a 3.99 ERA across 38 appearances, which included 19 starts and six games finished. In parts of three seasons with the Cubs, Montgomery has fashioned a 3.56 ERA in 99 games, including 38 starts and 22 games finished. Oh, and he recorded the final out of the 2016 World Series.

Through it all, Montgomery said he has learned that taking care of his whole body -- not just his arm -- is critical for the unpredictable nature of the role. He has added Pilates and yoga to his regular routine, for example, and improved his nutrition habits.

"All of those little things add up," Montgomery said. "I feel like it just ages you quicker when you are bouncing back and forth, because you never really get that solid routine. So, in order to counter that, you've just got to be in ideal shape to pitch."