Why Greene is the young ace to watch in '23

It's time to get excited about Hunter Greene … again.

There should be as much hype for Greene's 2023 debut as there was surrounding his big league debut in 2022, when he came out ripping 100 mph fastballs against the reigning World Series champion Braves and then set a pitch-tracking era record with 39 triple-digit heaters in his second career start against the Dodgers.

That was an incredible showcase of pure talent. But this could be the year that the 23-year-old -- who just spoke to 80 young players hoping to follow his path to the Major Leagues at MLB's DREAM Series this week -- emerges as one of baseball's best young aces-in-the-making.

Projections love Greene entering 2023 -- Steamer sees him as a top-25 pitcher by Wins Above Replacement, on the same level as Dylan Cease, Max Fried, Blake Snell and Zac Gallen, and projects him for 212 strikeouts, 11th-most of any pitcher.

Is that a surprise? Greene's rookie season was electric but rocky. For all the triple-digit heat, he fell off the radar a little as the year went on, going through a three-month stretch from May through July when he had a 5.49 ERA, then missing another month and a half with a shoulder strain. By the time Greene returned in mid-September, he wasn't exactly dominating the headlines.

But his end-of-the-season run was dominant. In four starts, one against each of the Reds' four divisional opponents, Greene posted a 0.78 ERA and 14.5 K/9, and he notched the first two double-digit strikeout games of his career.

What changed? Greene figured out how to get the most out of his 100 mph fastball in a way he hadn't all year. Here's what he did to close out the season vs. what he was doing at his low points.

In his first month in the big leagues, Greene brought the heat. He threw his four-seamer over 60% of the time in April, with about 30% sliders. But in May and June -- perhaps in an effort to be less predictable, perhaps because of the impeccable results on his slider (hitters went 0-for-25 against it) -- Greene completely changed his repertoire. He threw more sliders than fastballs over the next two months (48% sliders, 47% four-seamers). He also had a 5.63 ERA.

Down the stretch, he learned to love his fastball again. In September and October, Greene was back to throwing over 60% four-seamers, with 34% sliders, the same usage pattern he started with. But those fastballs were even better than they were before -- harder and more explosive.

Greene's four-seamer averaged 99.8 mph in September/October, not just his highest for any month, but the highest by any starting pitcher in any month of the 2022 season, ahead of the 99.3 mph Jacob deGrom averaged in August. Nearly half of the fastballs he threw were 100 mph or harder.

With Greene's increase in his already elite velocity came an increase in spin rate and "rise." His four-seamer averaged a season-high 2,401 rpm in September, and it was dropping a season-low 11 inches on its way to the plate.

So Greene started elevating more aggressively. When his power fastball got to its most powerful level of the year, he started throwing it at its highest level of the year. Over the final month, nearly two thirds of Greene's fastballs were high fastballs -- he threw 64% of his four-seamers to the upper third of the zone or higher. And he located 37% of his four-seamers right on the top edge of the zone or just above it in the "chase" zone for hitters.

In May and June, by contrast, only about half of Greene's fastballs were elevated (52%), and just over a quarter were on the top edge or high chase zone (28%).

More fastballs, harder fastballs, fastballs with more spin and higher fastballs turned into more swing-and-miss fastballs. Greene generated a 40% whiff rate against his fastball in September and October, second best among starting pitchers, just behind Eric Lauer. His 50 total swinging strikes on his fastball were the third most by any pitcher over the final month, behind Carlos Rodón and Lance Lynn. When Greene elevated his four-seamer, hitters swung and missed over half the time. His 51% whiff rate on high fastballs was the best mark by any starter for September/October.

With hitters swinging and missing so often, Greene's fastball became his No. 1 putaway pitch. That was not the case earlier in the season.

After the success he saw on his slider in April, Greene started using it heavily to try to strike hitters out over the next few months. In May and June, he threw his slider 62% of the time with two strikes and only threw his fastball 38% of the time.

But down the stretch, he went back to his heater. Greene's two-strike usage flipped in September -- he threw 58% four-seamers and 41% sliders. And when he threw his fastball with two strikes, he got the K well over a third of the time, posting the highest putaway rate on four-seamers among starting pitchers for the final month of the season.

Greene racked up 26 strikeouts on his fastball in September and October, second most of any pitcher behind Brandon Woodruff -- and Greene didn't return until Sept. 17, enough time for only four starts to Woodruff's seven.

Eighteen of those K's came on triple-digit heat, double the amount of any other pitcher in a single month of the season (Ryan Helsley had nine in July) and triple the amount Greene had in May and June combined (six).

In fact, during the final month of 2022, Greene recorded each of the four fastest strikeout pitches by a starter all year.

Fastest K's by SP in 2022

1. Hunter Greene: 102.4 mph -- Sept. 17 (Nolan Gorman)
2. Hunter Greene: 102.1 mph -- Sept. 17 (Paul Goldschmidt)
3. Hunter Greene: 101.9 mph -- Oct. 3 (Seiya Suzuki)
4. Hunter Greene: 101.8 mph -- Sept. 17 (Andrew Knizner)

The threat of him unleashing that fastball on the league in 2023 is why everyone should be watching Greene when he takes the mound.