This story was excerpted from Adam Berry's Rays Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

ST. PETERSBURG -- Shane McClanahan was sitting in the visitors’ dugout in Houston near the end of last season when he started talking about the process of continual improvement. After finishing 2020 with a historic postseason debut and a scoreless inning in the World Series, he wasn’t satisfied. He wouldn’t let himself be.

“The second you get content with anything, it's game over,” McClanahan told MLB.com before the final start of his rookie year. “Like Clayton Kershaw, probably one of the best pitchers to ever step foot in this world, won the Cy Young and the very next year debuts a brand new slider. It just shows, no matter what you do, don't be complacent. Always try to look for that next thing you can do to get better.”

Those were not just words from McClanahan. It was a mission statement he’s followed to become one of the game’s best young starters.

Last season, the Rays’ left-hander revamped his pitch mix, essentially creating two new breaking balls, and dramatically improved his command as he became the Rays’ No. 1 starter in Tyler Glasnow’s absence. This year, McClanahan has continued to evolve. The 25-year-old has taken what could’ve been perceived as the weakest pitch in his arsenal -- his changeup -- and made it into an undeniable asset.

As a pitch used exclusively against right-handed hitters, the changeup accounted for 8 percent of McClanahan’s offerings last year. He’s still only throwing it to righties, but McClanahan has upped his changeup usage to 19.4 percent heading into Tuesday night’s start against the Marlins at Tropicana Field.

In other words, McClanahan has turned what was his fourth pitch into a vital part of his arsenal without sacrificing the quality of anything else he throws, becoming a true four-pitch starter. And his newest weapon has been tremendously effective.

Opponents have just one hit against it, a Javier Báez single last week at the Trop. McClanahan has used his changeup to finish 14 strikeouts, 10 more than all of last season, while producing a mind-boggling 51.5 percent whiff rate with it. That’s better than even his wicked slider (45.9 percent) or curveball (40.5 percent), which might be two of the better left-handed breaking balls in all of baseball, as a complement to his high-90s fastball.

Just look at this comparison put together by MLB.com’s research team.

None of this happened by accident.

“That was a focus point last year,” McClanahan said recently. “I went into this offseason knowing that I had a lot of things to work on and improve upon, and I got back with [pitching coach Kyle] Snyder after the lockout and we went from there. We made some adjustments, and it's been having success so far.”

McClanahan credited Snyder, who also helped him develop his slider heading into last season, for leading the charge on his improved changeup. McClanahan said all it took was “just a little bit of an adjustment in the way I throw it, nothing major,” but the result of that work has been significant.

Compared to last season, McClanahan has added about three inches of vertical movement and a little more than an inch of horizontal movement to his changeup, and he’s locating it well. It’s become one of the most effective offspeed pitches of its kind in MLB. According to Statcast’s Run Value, it’s the fourth-most productive changeup in the Majors behind the Dodgers' Tyler Anderson, Rays teammate Jeffrey Springs, the Padres’ Nabil Crismatt and the Marlins’ Pablo López.

“He's really upped his unpredictability, because he's really throwing all four pitches about evenly,” Snyder said recently “Overall, he's just evolved through the early portion of the year.”