North Shore Tavern Mound Visit: How real was Triolo's September?

There's an old baseball adage to not put too much stock into September stats. Sample sizes are small, rosters expand and its not uncommon for a Pablo Reyes or John Holdzkom to piece together a great month just to be exposed over a 162-game campaign the next year.

That's why it's fair to be skeptical of Jared Triolo's final month of the season. After hitting just two doubles and one home run in his first stint in the majors, totaling 36 games played and 137 trips to the plate from June 28 to Aug. 15, Triolo went off in the final weeks of the season, doubling seven times with two homers in 18 games played. He had three times as many extra-base hits in September in half as many games.

Part of that slugging spike comes from a mechanical change, which Michael McKenry illustrates here. Triolo was much more upright with his stance down the stretch, and a tweaked hand position seemed to help him get the barrel to the ball more consistently:

It wasn't just extra-base power, either. Triolo also drew 12 walks in 72 trips to the plate (16.7%) and posted a .350 batting average and .458 on-base percentage that final month. That's the highest OBP of any Pirate in their first September, according to Stathead (min. 70 PA). In total, his 1.025 OPS was the second-best September for a Pirate rookie ever, just behind Ke'Bryan Hayes in 2020:

It's a small sample size, and it's unfair to project Triolo as a batting champion next year, but can he be a regular part of this lineup in 2024?

He's not going to play his natural position at third too often because of Hayes, but first base is pretty wide open at the moment. (Though I would expect the Pirates to look at external options this winter.) He also held his own at second base and can fill in as an outfielder and shortstop. Even if he doesn't have a set position in the everyday lineup, there's a pathway for him to play 100+ games because of that defensive versatility. Of course, he is going to have to hit to earn that playing time.

So which Triolo should we expect to see more of in 2024? The one who had a .314 slugging percentage over almost two months, or the September version? Talking to Andy Haines at the end of the season, he is inclined to believe it's the latter.

"Honestly, I believe this is who he is," Haines told me. "You look at the underlying components and how they've trended up in such a drastic favor. He's hitting the ball much harder and the impact is there, and the other traits aren't going away. You watch him, it's like the definition of a baseball player, man."

Triolo may not have had quite as high a pedigree as some of the hitters the Pirates called up this year, but he was still the team's No. 15 prospect, according to Baseball America, with decent offensive peripherals and results in the minors. Some of those good peripherals translated to the majors. His 26.6% chase rate was well below the league average (31.9%). He walked in 11.5% of his major-league plate appearances. He also hit the fastball very well, batting .350 with a .371 expected wOBA against four-seamers and sinkers.

Not chasing pitches out of the zone and hitting major-league fastballs is a great foundation for a big-league hitter. When Haines talked about his good traits not going away, look at these areas. Especially since it's probably no coincidence that Triolo's worst stretch at the plate coincided when he was chasing the most:

It's also likely not a coincidence that Triolo's September spike in OPS came when his fly ball percentage was climbing to new heights:

Those aren't cheap fly balls, either. Triolo does a good job getting the barrel to the ball, resulting in a "sweet spot" launch angle on 39.5% of his batted balls. That sweet spot is a launch angle falls between 8 and 32 degrees, which will produce quality line drives and fly balls. In September, 46.2% of his batted balls fell in that range, which is basically what Freddie Freeman did for the Dodgers last season. On the year, his 39.5% sweet spot rate ranks 24th among the 362 hitters with at least 200 plate appearances last year.

So you have a hitter who ranks in the top 10% of a stat that measures quality of launch, and the batted balls he has in that range are usually hit hard:

That's a good recipe for success. Triolo hit the ball harder in September (90.4 mph exit velocity, compared to 85.5 mph in July), which when paired with a better attack angle from his stance and better launch off the bat led to one of the best final months for a Pirate rookie ever.

Not to be a buzzkill, but the league will adjust.

Triolo feasted on pitches belt-high and up in the zone, but couldn't consistently elevate on pitches at the knees. If I was a pitching coaching scouting him out for next year, I would start there:

I heard from a scout last year that Triolo's swing can get flat. That could explain why we saw such a rise in fly balls when he went more upright, while he isn't able to club the low pitches like some hitters who have golf swings do.

There are some other red flags, too. He struck out in about 30% of his trips to the plate, including in September. His .514 BABIP that last month is also not maintainable (though a .382 expected wOBA is still terrific). He also only has one outstanding offensive month on his resume. All of this needs to be considered as the Pirates navigate a pivotal offseason and try to figure out where Triolo fits into their 2024 plans.

But when assessing the year as a whole, Triolo took a big step forward and should be a part of those plans moving forward. So when looking at that September, it may be better to focus on if he can can continue to show those positive traits over can he replicate those results.

"It's certainly not going to be easy. It's not for anyone," Haines said. "But I think Jared's a difference-maker for us."