Over six innings, Rodriguez allowed five hits and a run, walking two and striking out nine. He left with a 2-1 lead but wound up with a no-decision when the Cubs rallied to tie it in the seventh.
There was that one misfire to Kris Bryant that last season's National League Most Valuable Player pummeled over the Green Monster. But other than that, Rodriguez appeared to be putting his pitches wherever he wanted.
"He did a great job," said Red Sox catcher Christian Vazquez. "His changeup was the best changeup I've seen from him. He pitched, I think, the best game that I've ever seen from him."
The performance came on the heels of a six-inning, one-hit, scoreless performance against the Orioles.
Rodriguez has always had stuff. But as is the case for most young pitchers, command is the final piece. Once that comes, the true momentum starts.
In Sunday's contest, Rodriguez could essentially be a two-pitch pitcher because his fastball and changeup were complementing each other so well. He wound up throwing 66 fastballs and 29 changeups among his 108 pitches. The changeup generated nine swings and misses.
"I felt it was possible to command my pitches well, especially my changeup tonight," Rodriguez said.
When the Red Sox got swept by the Indians in the American League Division Series last October, it prevented Rodriguez from tasting what it is like to pitch big games in October. After Sunday, he thinks he has a better idea of how it would feel.
"It must feel like this because there's a lot of history between those teams and to face them got me really excited to have the opportunity," Rodriguez said.
With David Price sidelined for at least a few more weeks with a left elbow strain, the Red Sox are counting on Rodriguez more than ever.
The 24-year-old Rodriguez will surely have more confidence after a night like Sunday.
"I'm sure tonight is a big boost for it, particularly against that lineup," said Red Sox manager John Farrell. "The setting is one thing but his ability to go out and make really good pitches in key moments is a big development in its own right."