If there is one mistake universally acknowledged by Red Sox ownership, it's letting Jon Lester walk in 2014.
"I think we blew the Jon Lester -- we blew that signing in spring training," owner John Henry said in 2019.
A year later, chairman Tom Werner concurred.
"I go to sleep at night thinking that maybe we could've made another offer to Jon Lester that maybe would've bridged the gap," he said.
That single decision triggered a cascade of missteps, from the "He's the Ace rotation" that finished last in 2015, to the massive David Price contract in free agency, to the ill-advised Chris Sale extension that kicked in just as he underwent Tommy John surgery.
The Red Sox will never undo that mistake. But there's still time to make amends with a reunion that could be perfectly timed for both parties.
Lester likely made his final Cubs start at Wrigley Field on Wednesday, tossing five innings in a 3-2 victory over the Indians. With the best-of-three first round of the playoffs and the rest of the postseason taking place in a bubble, it's likely that Lester won't start another game in Chicago in a Cubs uniform.
His six-year, $155 million extension includes a $25 million team option for 2021, and after the game Lester sounded like someone who doesn't expect it will be picked up. That means the 36-year-old could be heading back into free agency at precisely the moment the Red Sox are desperate for starting pitching.
Perhaps Lester can come home again.
"We don't know what the future holds," Lester told reporters, including ESPN's Jesse Rogers. "A lot of emotions going into tonight. ... A lot of things on my mind. This year hasn't been easy for a lot of reasons. I'm not sitting here saying 'woe is me' because there's a lot of people worse off than me. A lot of emotions coming into this. Don't really know what to say, how to take it. A lot of uncertainties going forward."
It's hard to believe that Lester's time in Chicago already could be drawing to a close. It feels like yesterday that the Red Sox won it all in 2013 with Lester playing a central role and then almost immediately low-balled him the following spring, opening with a four-year, $70 million offer that Lester's side didn't even counter.
Rather than let him walk in free agency, the Red Sox traded their greatest homegrown pitcher since Roger Clemens to the A's at the 2014 trade deadline, hoping they could re-engage with him in free agency. But their six-year, $135 million offer fell well short of Chicago's, and so he departed for the Windy City to reunite with Theo Epstein.
A year later, he won 19 games, finished second in the National League Cy Young voting, and most importantly, led the Cubs to their first World Series since 1908.
Chicago has never once regretted its investment, which simply served to remind the Red Sox of what they had lost.
There's no telling what role Lester could've played during Boston's postseasons runs from 2016 to 2018, which included two first-round exits and a championship that, to be fair, might not exist without Price. The Red Sox tired of the left-hander's negative attitude, however, which played a role in dumping Price on the Dodgers as a condition of acquiring Mookie Betts.
Now the Red Sox find themselves rebuilding and in desperate need of short-term rotation help. Lester, who turns 37 in January, could fill that role perfectly. It also wouldn't hurt from a PR standpoint, which no small thing when your product is pulling a 0.4 TV rating opposite the Patriots.
After making his fifth All-Star team in 2018 and winning an NL-best 18 games, Lester's performance has dipped over the last two seasons. He's 15-12 with a 4.56 ERA in that span, and his average fastball has dropped below 90 mph for the first time in his career.
There are no perfect solutions for the Red Sox, however -- not with money tight and the rotation in shambles. There would be something poetic about Lester finishing where he started and potentially adding to the 110 wins he has already recorded in a Red Sox uniform.
"Going back to 2014, I didn't get to walk off the field like I wanted to at Fenway," Lester said on Wednesday. "Having an empty stadium (in Chicago) -- not how I envisioned my last start here."
There's still time, it turns out, to right at least one of those wrongs.