MILWAUKEE — David Peterson had already exited Citi Field after Wednesday’s doubleheader when New York Mets president of baseball operations David Stearns called to inform the homegrown pitcher that he was traded to the Chicago Cubs, a development that produced a mixture of shock and excitement.To that point, Peterson, a first-round pick in the 2017 draft out of Oregon, had spent his entire professional career in the Mets organization. He eventually blossomed as a starter, pitching in the 2024 National League Championship Series and last year’s All-Star Game. With Steve Cohen’s money and Stearns’ vision, the Mets hoped to rewrite their history and build something both special and sustainable.Instead, it all came crashing down on a big-market team with a projected $365 million payroll, per FanGraphs. The Cubs swept that series in Queens, winning four games in three days by a combined 33-17 score. The Mets committed six errors in the second game of that doubleheader before Stearns finalized the deal that flipped Peterson for Class-A hitter Cole Mathis.The Cubs instructed Peterson, who had a tenuous spot in New York’s rotation and a 6.09 ERA, to take time to organize things at his Long Island home. He reported back to Citi Field on Thursday in time to make the Cubs’ flight to Milwaukee, where he will face the first-place Brewers on Saturday night at American Family Field.By Friday morning, the Mets announced the firing of Carlos Mendoza, a well-respected manager who could not fix all the roster flaws that led to a 34-47 record.“I can’t speculate on everything,” Peterson said. “On the field, I just don’t think we were able to put all the aspects together at the same time. You go through some of the similar stuff as everyone else with the injuries. Losing (Juan) Soto, him coming back, (Francisco) Lindor going down, that’s all normal. We just weren’t winning. At the end of the day, that’s the simplest way to put it. We weren’t getting the job done on a daily basis. We put the organization in a spot where they had to make some changes.”The Mets' troubles don't solely belong to former manager Carlos MendozaEscape from New York is one angle to this deal. The Cubs believe Peterson, a 6-foot-6 lefty with a career groundball rate of 51.5 percent, will benefit from a vastly improved defense and solid game-planning system. After 10 seasons in the same organization, he may also be more receptive to new voices.“We all can acknowledge that sometimes a change of scenery is a good thing,” Cubs manager Craig Counsell said. “When things aren’t going well, sometimes a fresh start is something that can kind of reenergize you, refocus you, and hopefully get you to a good place. Hopefully, we can provide that.”Peterson won’t be looking over his shoulder. The Cubs have 11 pitchers from their 40-man roster currently on the injured list, a vicious cycle that has eroded the organization’s pitching depth. That sense of urgency forced Jed Hoyer’s front office to make the deal nearly six weeks before the Aug. 3 trade deadline.Peterson, 30, is months away from becoming a free agent, when his perceived value could be much higher after a half-season surrounded by Gold Glove defenders in Dansby Swanson, Nico Hoerner, Alex Bregman and Pete Crow-Armstrong.“It’s huge,” Peterson said. “You look at the guys that are around the infield, and the defense as a whole, it’s hard not to be excited about that group. You see statistically they’re at the top of every list.”Consistent, high-level defense won’t be enough to overtake the Brewers. Not when Jacob Misiorowski is opening with a 105.5 mph fastball, taking a no-hitter into the fifth inning and looking like one of the most dominant pitchers of this era.Seiya Suzuki’s home run off Misiorowski and late sacrifice fly were the sum of Chicago’s offense during Friday night’s 6-2 loss in front of a sellout crowd of 41,021. The Brewers did almost all of their damage against middle-innings relievers out of a makeshift bullpen.Counsell has stressed this isn’t an either-or situation, choosing between a healthy, functional pitching staff and a lineup that performs up to expectations. To make the playoffs, the Cubs have to execute in all phases of the game on a consistent basis.The first half of this season wasn’t always pretty. Milwaukee’s 7 1/2-game lead in the division — while carrying a payroll in the range of $145 million — doesn’t reflect well on Chicago’s operation. But the Cubs have given themselves a chance by finding solutions and avoiding the worst-case scenario that enveloped the Mets.Now that it’s here, even Peterson recognizes the potential upside to a change of scenery.“When I was there, my whole goal and focus was to help the Mets win games,” Peterson said. “But I do think there is something to that. I’ve seen it with other guys. I’ve seen it with friends in the game where they’re kind of stuck in a rut or stuck in a spot that they’re not necessarily enjoying, and they’ve gone somewhere else and had a lot of success. That’s part of what gives me excitement about this opportunity.”