First there was the slide, and then there was the career slide for Dustin Pedroia.

In April 2017, in a game between the Boston Red Sox and Baltimore Orioles, then-Orioles third baseman Manny Machado made an aggressive and arguably dirty slide into Pedroia at second base. He hit Pedroia's calf and indirectly injured his left knee:

You can argue the aggressive vs. dirty distinction. To his credit, Machado immediately put his hands on Pedroia with seeming concern.

Later, Machado told reporters the takeout nature of the slide "wasn't intentional."

Here's another important factor: Pedroia underwent surgery to repair a torn meniscus in his left knee in October 2016, meaning he was already potentially compromised in that area.

Here's what's undeniable: Pedroia played hobbled for the remainder of the 2017 season. He landed on the disabled list twice in August that year with left knee inflammation and underwent another knee surgery that October.

He appeared in just three games in 2018 before again going down with left knee inflammation and was a spectator during Boston's World Series championship run.

This season, he began the year on the injured list, was called up after a rehab assignment and went 2-for-20 before he tweaked his left knee on a swing.

It wasn't catastrophic; he's set to begin another rehab assignment Thursday with Double-A Portland. He'll be wearing a new kind of knee brace, according to Jason Mastrodonato of the Boston Herald.

"We'll see how it goes," Red Sox manager Alex Cora told reporters.

Boston fans are permitted to hope for the best. But they should also prepare for the worst. When an injury lingers across three seasons, that's a bad sign.

When it happens to a guy who's 35 years old? In the parlance of the magic eight ball, "Outlook not so good."

Not so long ago, Pedroia was the heart and soul of the Red Sox. In 2007, he won Rookie of the Year honors and helped Boston win its second Fall Classic in four years, following the curse-busting title of 2004.

The next season, he added an American League MVP trophy to his case as he paced baseball in hits and doubles and snagged a Gold Glove for his work at the keystone sack.

From 2009 to 2014, he earned three more Gold Gloves, made three more All-Star appearances, enjoyed a pair of top-10 MVP finishes and won another ring.

More than the numbers and hardware, however, Pedroia embodied the scrappy spirit of Beantown. Listed at just 5'9" and 175 pounds, he's no one's idea of imposing. But the results were there.

Certainly other players, including David Ortiz, deserve a large share of credit for guiding Boston during those years. (Ortiz was around for three championships.)

But Ortiz is retired. Pedroia remains...for now.

In baseball, past success and fan-favorite status can carry you only so far. In Pedroia's absence, top prospect Michael Chavis has gotten reps at second base and has a 1.071 OPS and three home runs in nine games.

Boston will undoubtedly give its former MVP another opportunity if his knee holds up. He's signed for $13 million in 2020 and $12 million in 2021. Still, it feels like the last chance for Pedroia to be a significant part of the team he once led is fast approaching.

So, back to the slide that started the, well...slide. Is Pedroia angry at Machado?

"What is this, high school?" Pedroia said when asked that question prior to the 2018 World Series (when the Red Sox played Machado and the Los Angeles Dodgers), per Christopher Smith of MassLive.com. "I'm a grown-ass man, dude. Come on."

That said, he also told WEEI's Rob Bradford he thinks about the play "all the time."

Why wouldn't he? It was the turning point that led to a cascade of surgeries and re-injuries and underperformance and may have spiked a great career.

All statistics and contract information accurate entering play Tuesday and courtesy of Baseball Reference.