What to expect from Guardians' Bibee in the big leagues

The Guardians have made a habit of drafting polished college pitchers and helping them upgrade their stuff, turning them into big leaguers with ceilings higher than initially expected. Cy Young Award winner Shane Bieber is the most famous example. Tanner Bibee is the most recent.

A fifth-round pick out of Cal State Fullerton in 2021, Bibee made just 28 Minor League starts before getting summoned to Progressive Field. He excelled in his Major League debut last Wednesday, beating the Rockies by allowing just one run on six hits in 5 2/3 innings, striking out eight and walking none. The 24-year-old right-hander threw 60 of 91 pitches for strikes and fanned five straight hitters at one point.

That Bibee pounded the strike zone is no surprise. He did that for four years of college, posting a 3.82 ERA and a 236/73 K/BB ratio in 271 innings with the Titans before signing for an under-slot $259,400. But his arsenal has improved dramatically since then.

In his final season at Fullerton, Bibee averaged 92 mph with his fastball and backed it up with a mid-70s curveball that he favored over his low-80s slider, as well as a barely used low-80s changeup. He didn't even crack MLB Pipeline's Guardians Top 30 Prospects list until nearly a year after he turned pro.

• MLB Pipeline | Top 100 prospects | Prospect video

Rather than have Bibee make his pro debut in the summer of 2021, Cleveland had him focus on adding strength and refining his delivery and pitches. The results were dramatic when he took the mound in 2022, rocketed to Double-A in July and finished the season among the Minor League leaders in ERA (2.17, sixth), K/BB ratio (6.2, sixth), WHIP (0.97, eighth) and walks per nine innings (1.8, 10th).

Now ranked No. 58 on the Top 100 Prospects list, Bibee has completely transformed his repertoire. His fastball now sits at 94-96 mph and reaches 99 with carry and armside run, and he still commands his heater better than most pitchers do.

Bibee's slider is now his go-to secondary pitch and he used it to finish five of his strikeouts against Colorado. It has become a plus offering with sharper sweep that parks at 82-84 mph and peaks at 87, and he also can turn it into a harder cutter when he wants.

Bibee's fading changeup has some added power as well and now arrives at 83-85 mph while continuing to baffle left-handers. His curveball is his lone pitch that hasn't made a jump and he doesn't use it as much as he did in college, employing it mostly to give hitters a different, slower look.

Once viewed as a potential back-of-the-rotation piece whose fastball command was his best attribute, the transformed Bibee now looks equipped to pitch in the front half of a starting five. He drastically changed his ETA and after it was initially unclear whether he'd make more than just an emergency start, he'll get the ball again Tuesday against Gerrit Cole at Yankee Stadium.

Cleveland's rotation is experiencing some turbulence, so Bibee may stay for a while. With his combination of stuff and control, he's poised to succeed.