The pitcher many scouts think has the highest upside in the 2020 MLB draft has been seen by most big league organizations for just three innings. And those innings were nearly a year ago, when he was part of the 2021 draft class, so some scouts weren't even paying attention to him.

His spring high school season was canceled before it even started. But he's been rising on some draft boards because he has impressed in Zoom interviews and has been posting videos on social media that show big league-caliber stuff coming out of the hand of a 17-year-old. He hit 98.5 mph last week and delivers some of the advanced pitch data that clubs covet, which he's been measuring in a warehouse in Pennsylvania while getting remote training from a top independent facility over the internet. Still, scouts aren't allowed to watch or talk to him in person.

With all that, he might be one of the top 10 picks on the night of June 10, and he will certainly be among the first 37 selections. At a time when little seems normal in the world, this is the setting for the rise of the MLB draft's mystery man, Nick Bitsko.

ESPN has obtained the Rapsodo pitch data from all of Bitsko's recent bullpen sessions, data no MLB team has seen, aside from small parts Bitsko has posted on Twitter and Instagram in the past few weeks. I'll break down that data and share some of the raw numbers to tell you what MLB clubs would think about the information (if they had it), in combination with their scouting looks, because I saw two of those three innings last summer and I've been in draft rooms where these sorts of discussions have happened.

Also see:

McDaniel's MLB mock draft 2.0

How the abbreviated 2020 draft impacts this year and beyond

McDaniel: The top 100-plus players available in 2020

Most teams have seen Bitsko throw only a handful of competitive innings, all last summer in showcase environments, before his January announcement that he had reclassified into the 2020 draft class. Because of that, this data will have a significant impact on his draft status. Meanwhile, clubs that have had video interviews with Bitsko laud his makeup and mental approach.

The data reveals that Bitsko's fastball is already truly elite, comparable with some of the best fastballs in the big leagues. He averages 99.6% spin efficiency on his fastball, which means he is achieving almost perfect backspin on a four-seamer. Bitsko's raw spin rate is slightly above MLB average, and that enables all of the spin on the ball to go toward "lift" or the vertical movement, hitting the mitt inches above where the eye would expect it to go.

According to Baseball Savant, the highest fastball spin efficiency in the big leagues belongs to Justin Verlander at 98.5%. Bitsko's spin efficiency (aka active spin) will vary a bit when he's throwing in game situations and when measured on TrackMan or HawkEye technology in a stadium instead of Rapsodo in a warehouse, but the elite characteristic is obvious.

Bitsko's 19.1-inch vertical break (an above-average amount of "lift") in conjunction with a fastball that sits 92-96 and hit 98.5 mph this week has comparables in the big leagues that include the fastballs of Lucas Giolito, Mike Clevinger, Liam Hendriks, Nick Anderson, Emilio Pagan, Roberto Osuna and Pedro Baez among the 10 most similar qualified fastballs using velocity, spin rate, spin efficiency and movement as inputs. Among starters with at least 120 innings pitched in 2019, Giolito had the seventh-best and Clevinger the ninth-best fastballs in baseball per FanGraphs' pitch value metric. Among relievers, Hendriks was sixth, Pagan was ninth and Baez was 30th.

The average age of Bitsko's top 10 fastball comparables is 29. Bitsko will be 17 for a few more weeks.

Bitsko's breaking stuff has markedly improved in terms of these metrics while he has been training remotely with Driveline Baseball from his home in Pennsylvania, and it improved again in his most recent bullpen on Friday. His curveball and slider aren't currently elite big league pitches, but that's an unreasonable expectation since that would make Bitsko the greatest pitching prospect of all time. Once we step back and realize where he is in his development trajectory, it's impressive enough that he shows characteristics for both breaking pitches to become above-average major league pitches down the road as well.

Bitsko's curveball has true 12-to-6 action that allows him to use it against lefties and his slider against righties, as his changeup lags behind as a fourth pitch at the moment. His curveball ranges from 77 to 80 mph and averages minus-12 inches of vertical break, which plays up given the opposite, rising shape of his four-seam fastball. Bitsko's slider averages 86 mph, which is harder than the average MLB slider and among the hardest you'll ever see for a 17-year-old. The spin efficiency of his slider is 29% where 0% is pure bullet or gyro spin, the platonic ideal of a slider. The lowest rate in the big leagues is just a hair over 9%.

These were impressive figures until his bullpen last Friday, where Bitsko improved both breaking balls markedly after getting feedback and making adjustments. The newer version of his curveball was a bit slower at 76-78 mph and with a slightly lower raw spin rate, but his spin efficiency -- the kind of spin that creates movement in a curveball -- went from 54.5% to 66.5%, so the sink on the pitch increased by 2.4 inches to minus-14.4 inches. The best comparable for his earlier incarnation of the curveball was the curveball of Giants righty Shaun Anderson and the best comparable for the newer version is that of Padres righty Chris Paddack.

On the slider, Bitsko also took a little pace off the pitch, throwing it 4.0 mph slower but getting the spin efficiency from 29.2% down to 4.2%, much closer to the goal of 0% and, like the spin efficiency of his fastball, better than anyone in the big leagues, with the same caveats applying. The best comparable for his new slider is that of Reds righty Luis Castillo.

It's somewhat lucky that Paddack and Castillo are the new single best comps, because both are very successful young big league starters, but that also makes Bitsko's current ability sound a bit better than it is. Both Paddack and Castillo use a changeup as their primary off-speed pitch. Castillo's slider (17% usage, run value is basically league average) and Paddack's curveball (10% usage, also roughly average run value) are tertiary pitches for top pitchers.

Looking at it another way, Bitsko's raw stuff -- the velocity and movement of his four-seam fastball, slider, curveball -- has all the quality of current big league starting pitchers and could plausibly be the arsenal for a current big league starter. And he's still 17 with a limited track record of pitching.

The magic of this data is allowing us to reasonably compare the pitches of a teenager in a warehouse in Pennsylvania, who is as lightly scouted as any first-round pitcher in recent memory, to those of some of the best pitchers in baseball. Even crazier, these comparisons aren't that off-base. The interplay of pitches, command, deception and in-game adjustments are the things that the sort of analysis performed above can't completely quantify, though they are unquestionably the crucial building blocks of any successful pro pitcher.

There's still some tweaking to be done with these breaking pitches, to throw the curveball a bit harder, get more true topspin to increase the spin efficiency, to improve the shape of the slider, but that gap was closed a bit in just the past week. Bitsko's changeup currently comes out of his hand very similarly to his fastball, which is very common for young pitchers. Ideally, the pitch comes out with side spin (think spinning like a basketball being spun on someone's finger), which is achieved by tinkering with grips, hand position and different cues from coaches. This is why it's common to hear about a pitcher's changeup dramatically improving with just a tip from another pitcher or coach.

It's typical for teenage pitchers to need years to tweak these things with extensive hands-on professional instruction and discovery, far more than the few months of remote training during a pandemic that Bitsko has had so far. Since Bitsko reclassified in January to the 2020 class, he's being compared to 2020 class pitchers such as Texas prep right-hander Jared Kelley, who has been throwing in the upper 90s for years and for much of each year thanks to the warm climate. Bitsko had only two years of cold-weather high school competition with limited innings over the summer for a travel team and he's also 8-10 months younger than his main competition. It also helps that his coachability and work ethic are perceived as pluses by the industry due in large part to what he has been posting on social media about his workouts, with hard data attached.

Bitsko's two scouted summer outings against the 2020 class yielded a slightly different report from scouts' eyes than this data-driven one. His fastball sat in the mid-90s and is graded similarly by scouts, but his downer curveball drew potential plus grades while his slider was seen as a notch behind, whereas the data suggests they're more comparable now. One of the weaker points of Bitsko's résumé is the question of control and command, since some teams weighing whether to meet his multimillion-dollar price have seen him throw only three showcase innings and one March bullpen, along with this quarantine bullpen data.

The elements for a traditional 200-inning starter are present, but in every other case, teams have at least dozens of innings of eyewitness track record to help them make that decision. As of May 15, prospects can give data of post-quarantine workouts to all 30 clubs via MLB's Prospect Link database.

In a draft where no prospect has the full spring's worth of performance that clubs are used to having before they make a selection, teams are leaning more on data to stand in for those in-person looks. Some college pitchers are perceived to be slipping from where scouts had them ranked since they throw sinking fastballs, while (all things being equal) most of the league now generally prefers Bitsko's style of high-efficiency, four-seam fastballs with lift. This type of pitch both causes more whiffs due to the deceptive "rise" to the pitch, particularly when thrown at the top of the strike zone, and also enhances the effectiveness of a curveball at the bottom of the zone. This dual upside gives some margin for error in the development of pitchers who are still years away from the big leagues.

Right-handers Emerson Hancock of Georgia, Carmen Mlodzinski of South Carolina and Chris McMahon of Miami all throw two-seam or sinking fastballs and are predicted to go lower now than expected when the season was suspended. My latest mock draft has Bitsko being considered as high as eighth overall by San Diego, drawing interest from a number of teams in the middle of the first round including Philadelphia at 15th overall, and coveted by clubs picking in the 30s and 40s with extra picks and flexible bonus pools.