Alonso can't stop hitting 'clutch' homers

Pete Alonso has made himself known in a big way so far in his rookie year, letting his prodigious power do the talking from his spot in the Mets’ lineup.

That power was heralded before he came up to the big leagues, so it should come as no surprise that he already has six home runs with an exit velocity of 110 mph or higher, tied for second-most in the Majors. What might surprise you is the situations in which he’s hit those homers.

Alonso has 11 big flies in his career, all this season. And of those 11 homers, 10 of them have come off relief pitchers -- the most in the Majors this season. He's hitting .373 with a 1.430 OPS against relievers, compared to a .218 batting average and .648 OPS against starters.

So what's going on here? Let's dig in.

No relief against Alonso

As noted, 90.9 percent of Alonso’s homers this season have been off relievers, and nine of his 11 homers have come in the seventh inning or later. Obviously, that pace is almost certain not to hold up over the season, but it’s still worth examining. The highest percentage of homers off relievers in season with at least 20 homers was 69.6 percent, by Jed Lowrie in 2018, when he hit 23 homers total, with 16 of those off relief pitchers.

Highest % of HR off relievers (min. 20 HR)
1) Jed Lowrie, OAK, 2018: 69.6
2) Tim Salmon, ANA, 2002: 68.2
3) Stephen Piscotty, OAK, 2018: 59.3
4) Cal Ripken Jr., BAL, 1985: 57.7
5-T) Robin Ventura, NYM, 2001: 57.1
5-T) Jorge Posada, NYY, 2000: 57.1

However, nobody on that list reached even 30 total homers, which Alonso will do at his current pace. The highest percentage of homers off relievers in a 30-plus homer season was 56.7 percent, by Tony Clark in 2005. The highest in a 40-homer season was 51.1 percent by Chris Davis in '15. And in case you are wondering, the highest rate by a player in his rookie season with at least 20 homers that year was 52.4 percent, by Alexei Ramirez in '08.

With Alonso already up to 10 homers off relievers, it’ll serve us well to look at the raw numbers, too. The most homers off relievers in a season was 30, by Mark McGwire in 1998 -- when he broke the overall single-season record with 70. The most by a Mets player was 16, by Howard Johnson in '89. And the most by any player in his first season was 17, by Cody Bellinger in 2017. No other player besides Bellinger has had more than 13 in his first season in the Majors, which is good to keep in mind, considering Alonso is already at 10.

Most HR in a season off relievers

1) Mark McGwire, STL, 1998: 30
2) Chris Davis, BAL, 2015: 24
3) David Ortiz, BOS, 2006: 23
4) Sammy Sosa, CHC, 1998: 23
5-T) Andre Dawson, CHC, 1987: 22
5-T) Harmon Killebrew, MIN, 1961: 22
5-T) Carl Yastrzemski, BOS, 1967: 22

Of course, it doesn't matter whether the homer comes off a reliever or starter if it helps the team get back into the game or take the lead. Eight of Alonso's homers have come with the Mets tied or trailing, which is among the top five highest totals in the National League. When he homers, he's helping the Mets stay in the game or take the lead. Two of his homers have been go-ahead: a first-inning homer off Dakota Hudson and a ninth-inning blast off Adam Warren.

Why is this happening?

If we take a look at how Alonso has been pitched to this season by relievers as compared to starters, a few things stand out. First, 62.1 percent of pitches he's seen from relievers have been fastballs (four- and two-seam, sinker, cutter), compared to 54.2 percent from starters. Alonso has been crushing fastballs, with a .653 slugging percentage in at-bats that end on those pitches this season from all pitchers. If we specify it to relievers, he's slugging 1.061 against fastballs, compared to .308 against fastballs from starters. Seeing them more frequently from relievers has certainly helped him succeed in those late innings. Seven of his home runs this season have been off fastballs.

Another important component, which goes hand-in-hand with more fastballs, is more velocity overall: 10.3 percent of pitches Alonso has seen from starters have been 95-plus mph, whereas 16.7 percent of pitches he's seen from relievers have been thrown that hard. While catching up with elite velocity is sometimes an issue for older players, young Alonso has no such issue with flamethrowers. Overall, he's slugging .706 on the year against 95-plus mph heat, and it's a 1.273 slugging percentage on those pitches from relievers. He's seen a lot fewer of those from starters as noted, and slugged just .154 against them.

Something else he's seen more of -- though not at quite as drastic of a rate -- is pitches in the zone. 41.1 percent of offerings he's gotten from starters have been in the zone, compared to 44.2 percent from relievers. As you might imagine, he's done quite well against pitches in the zone, with a .756 slugging percentage, compared to a .271 slugging percentage on pitches outside the zone. When you're crushing pitches in those locations that much, any extra ones you can see there help. To that point, he's slugging 1.211 on pitches in the zone from relievers, compared to .423 on those from starters.

More than likely, we'll start seeing Alonso hit homers off of starters more frequently, but for the time being, the Mets (and their fans) can't help but enjoy all of these big homers in big spots.