Colin Rea's Success in Cubs Starting Rotation Will Depend on the Defense Living Up to Its Potential

For the last two seasons, the Cubs' theory—their plan and design for getting to the postseason—has been that they would have an elite team defense. They signed Dansby Swanson and slid Nico Hoerner to second base for 2023 to create an exceptional middle infield. They extended Ian Happ on the same premise, securing one of the league's best left fielders. In neither of the last two years, however, have they met that expectation for themselves.

In 2023, Chicago ranked eighth in MLB in Defensive Runs Saved (DRS) and 15th in Defensive Efficiency, a simple metric that divides outs recorded on balls in play by total balls in play. Last year, they were ninth in DRS and seventh in Defensive Efficiency. Those aren't bad numbers, of course. They've been markedly better than average. The problem is that they weren't built to be a team with an above-average defense. They were built to get a whole lot of their value from that sector.

With below-average strikeout rates in each of the last two years, the Cubs allowed lots of balls in play. Being better than most teams at converting those into outs is great, but if some of them come at the expense of strikeouts (which are almost always outs), then the team doesn't come out as far ahead as it needs to—especially given that the team was built around defense, at the expense of some offensive firepower.

After their offseason turnover, Chicago is a bit more prepared to win games by scoring runs in bunches than they have been in the past. To be the 90-win team they believe themselves to be, though, they'll still need to be better in the field. There's cause for optimism there, too, of course. The plan is to (mostly) take Seiya Suzuki off the field, replacing him with the much more competent Kyle Tucker in right field. Instead of two-thirds of the season, Pete Crow-Armstrong is penciled in as the everyday center fielder. Matt Shaw might not immediately contend for the Fielding Bible Award, but he's clearly superior to Christopher Morel at the hot corner. Carson Kelly should help the team control the running game better. After some growing pains, Michael Busch has become one of the best defensive first basemen in the game.

Colin Rea needs that great defense to be great, in a major way. He only struck out 18.9% of opposing hitters last year. He gets his outs by pounding the strike zone, and by inducing lots of middling contact. He posted a 4.29 ERA last season, despite giving up home runs at an above-average rate and not missing many bats, because he was well-managed and well-supported by a truly elite Brewers defense.

If they've built the team they hope they have, the Cubs will be able to offer Rea the same support. They amassed more bullpen depth this winter, so they have the option of pulling starters more proactively, as the Brewers did throughout 2024. They also have a defense with a real, more viable chance to be one of the two or three best in baseball. The hard part is still in front of them. They have to actually stay healthy enough and develop their young talent well enough to be an elite fielding unit. At the very least, though, they've positioned themselves to make pitchers like Rea more valuable—even if they end up needing him to make 25 starts or more.