There’s no way to say this without sounding snarky, so I’m not going to try: The Oakland A’s, who were supposed to be abysmal, have shocked the baseball world by being merely mediocre. They’re in third place in the AL West, with a full series’ worth of buffer between them and their pursuers. The Angels are suffering the mother of all post-breakup hangovers, and it appears that the Astros have finally been caught by Mephistopheles. Reports say a sinister-looking goateed man has been seen pounding on the door to Minute Maid Park, saying, “I gave you your two World Series, now I’m here for your soul!”

Nothing gold can stay.

The key — or at least one key — to Oakland’s surprising ascent to averageness has been a superb bullpen. Closer Mason Miller has grabbed most of the headlines; some people are saying he’s the best reliever in baseball now. I don’t know if that assertion will hold up over a full season, but the hyperbole will continue until the FIP doesn’t start with a minus sign.

Miller’s emergence has sucked up all the air in the room — insofar as there was ever a ton of air in the room for discussing Oakland’s bullpen — to the detriment of his teammates. So I wanted to highlight Lucas Erceg, who’s been very good this season, and is also kind of weird.

The first thing to know about Erceg is that he was, until very recently, a third baseman. As a sophomore at Cal, Erceg hit .303/.357/.502 with 11 home runs in 57 games, but was ruled academically ineligible the following season, which kicked off a circuitous path to the majors. First: A year at NAIA Menlo College, alma mater of former MLB… standout is probably too strong a word, even if he won a World Series and made an All-Star team… Gino Cimoli. Erceg went in the second round to Milwaukee, becoming Menlo’s highest draft pick ever in the process, and slowly worked his way through the minors with a series of unremarkable batting lines.

In 2021, the Brewers gave Erceg, who’d pitched occasionally at Cal, a shot as a reliever, and by that summer he was good enough to get an honorable mention on Milwaukee’s prospect list. (Even if it was only one sentence in a section labeled “Arm Strength.”)

In 2023, the A’s — who have had some success with converting college infielders into relief pitchers, or who at least brought Sean Doolittle through — purchased Erceg from Milwaukee. This furthers my long-held belief that everyone who plays for the Brewers will one day play for the A’s, and vice-versa. We’d save a lot of hassle by merging the two franchises and having them play on a barnstorming circuit called the John Jaha Highway.

But I digress.

Erceg’s surface stats look pretty pedestrian right now, but about half of his 3.38 ERA comes from one three-run blown save against the Rangers on May 6. At the end of April, he was on a run of nine consecutive scoreless appearances, the last eight of which were also hitless. It’s not as impressive as a hidden perfect game, but Erceg did throw a hidden no-hitter (with 13 strikeouts and three walks on 120 pitches) from April 11 to April 30. I regret not getting to this topic two weeks ago, because I would’ve hammered the “more like Lucas Goose-egg” joke until you all started sending me rotten vegetables in the mail.

Puns and unusual development plan withstanding, there are two things I want to highlight about Erceg: His unusual repertoire and the significant step forward he’s made in missing bats from last year to this year.

As you might expect from a conversion project, there are elements of Erceg’s game that might be considered crude. He’s a hard-throwing one-inning reliever, to start, and even after taking a substantial step forward in this department, his walk rate this year is 11.9%. That’s in the “survivable, but not ideal” bucket for a pitcher, even a reliever.

Nevertheless, Erceg has a legitimate four-pitch repertoire. And this isn’t some fastball-slider guy who has a show-me curveball and a changeup he occasionally throws to opposite-handed batters. He throws four pitches between 18.9% and 30.5% of the time, and while he has specialist offerings to both righties and lefties, he throws his four-seamer and slider against everyone, giving him a three-pitch repertoire against any opponent.

There are 15 pitchers this year who qualify for Baseball Savant’s leaderboards, throw at least four pitches 15% of the time, and have no more than a 20-percentage point spread between their most-used pitch and their least-used pitch. (Erceg’s spread is 11.6 percentage points, the third-lowest of his cohort.) Of those 15 pitchers, 10 have thrown most or all of this season out of the rotation. That makes sense, because the more times a pitcher goes through the lineup, the more pitches he needs.

Here are the five relievers, with the number of pitches they throw, the spread between their highest and lowest pitch usage rate, and the average velocity of their hardest fastball. (Hardest, because all five of these pitchers throw at least two types of fastballs.)

These guys aren’t soft-tossers — Brent Suter came up in the net I originally cast before I narrowed the parameters some — but Erceg is on a different planet, velocity-wise. His changeup is averaging 91.4 mph, which is just 0.3 mph slower than Farmer’s sinker. That changeup is getting knocked around — five of the seven extra-base hits Erceg has allowed this season have come off the changeup, including his only home run — but it’s also missing bats at a rate of 37.5%.

In fact, I’m going to combine arbitrary-endpoint theater and small-sample-size theater to give you a fun fact: Through the weekend, only three pitchers in baseball were running whiff rates of at least 28% on four different pitches they’d thrown at least 49 times: Zack Wheeler, Pablo López, and Erceg.

Now to the really fun part. Erceg has experienced a massive uptick in chase rate, from 23.2% to 31.0%, while at the same time lowering his in-zone swing rate from 62.9% to 56.1% and his in-zone contact rate from 79.3% to 67.2%.

In other words, hitters are swinging less at pitches in the zone, and when they swing they’re not making as much contact. And simultaneously they’re chasing pitches a third more than they did last year. It’s not immediately clear to me why this is happening; Erceg’s in-zone rate is down a couple percentage points, and while his overall opponent swing rate is up, it’s by about two swings at this point in the season. That’s nothing.

As with any reliever performance before the All-Star break, it bears monitoring before we start to count on it going forward. But for now, Erceg is getting whiffs on four different pitches, and is one of the best relievers in baseball both at missing bats and avoiding hard contact. Not bad for a converted infielder, and at best the second-most important reliever on the Oakland A’s.

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