To say that Diamondbacks hitters are struggling feels like an understatement.

Over their past six games, the Diamondbacks have scored a total of nine runs. Their team OPS in that span is .485. They have lost all but one of those games.

Thursday’s outing against the scuffling New York Mets was the latest example of their hitting woes. The Diamondbacks mustered only four hits, and none after the fourth inning. They had only two extra-base hits, both of which were doubles. Their last homer came on May 22.

Their offensive struggles span longer than a week, however. In the month of May, the Diamondbacks have a team OPS of .649, which ranks 27th in baseball and is the eighth-lowest mark in any month in franchise history.

Much of the attention has been placed on sophomore outfielder Corbin Carroll, who has posted a .562 OPS in a not-so-small sample size of 236 plate appearances. Entering play on Friday, only three qualified major league hitters had a lower OPS than Carroll.

Carroll is not the only struggling D-backs hitter, though. Eugenio Suárez, who was acquired in an offseason trade with the Seattle Mariners, has hardly outperformed Carroll with a .583 OPS.

Meanwhile, Diamondbacks 24-year-old catcher Gabriel Moreno, who seemed to be emerging as a middle-of-the-order threat late last year, has taken a step back with a .650 OPS. The always streaky Lourdes Gurriel Jr., whom the team re-signed over the offseason, has also struggled with a .648 OPS.

Even Ketel Marte, who had a 21-game hit streak going as recently as May 22, has gone just 1-for-24 since and now has a .689 OPS for the month.

Of course, the Diamondbacks’ May hitting woes cannot be attributed to one central cause. There are several problems that need fixing. Here are a few of them.

Diamondbacks missing mistake pitches

In Major League Baseball, only about eight percent of pitches land in the middle-middle portion of the strike zone. That means hitters better capitalize when they get one. The Diamondbacks have struggled to do so.

Suárez’s at-bat against Texas Rangers lefty Andrew Heaney on Tuesday was emblematic of this team-wide issue.

On paper, this was a decent matchup for Suárez. He hits lefties better than righties, and, while Suárez has struggled against velocity this year — more on that later — Heaney’s four-seamer only sits around 91 mph.

Two pitches in, Suárez found himself in a golden 2-0 count. Heaney has thrown 26 pitches in 2-0 counts this year, 23 of which have been four-seam fastballs. Suárez had to be looking heater.

Sure enough, he got it: a center-cut 91 mph fastball. And Suárez swung right through it.

The count was now 2-1 — still in Suárez’s favor.

Heaney then gifted Suárez another four-seamer right down the middle. This time, Suárez managed to make contact, but he rolled over to short with an exit velocity of just 75 mph. Out number two.

To be clear, this is not just a Suárez problem. He has actually been one of the Diamondbacks’ better performers on center-cut pitches this season.

As a team, the D-backs have hit just .247 with a .381 slugging percentage against middle-middle pitches this month, both of which rank 29th in baseball. For reference, the league averages are .317 and .574, respectively.

To be clear, this is not to say that the Diamondbacks should be among the league leaders in hitting center-cut pitches. In March/April, the team hit .310 with a .471 slugging percentage on such offerings, which ranked 19th and 25th, respectively. Last year, the club was middle-of-the-pack with a .332 average and a .471 slugging percentage on middle-middle pitches.

Expecting the team to rank among the leaders in that regard is probably unrealistic, but getting back to the middle of the pack in that regard would do wonders.

The Diamondbacks have seen only a modest drop-off in production on pitches in the shadow zone, which includes the area at and around the edges of the zone. In April, the D-backs hit .237 with a .372 slugging percentage on such pitches. In May, those numbers dropped slightly to .215 and .350, respectively, with the expected stats effectively the same.

The Diamondbacks are holding their own on the edges of the zone, but they’ll need to do more damage in the middle of the plate to be successful.

Trouble with velocity

The Diamondbacks opened the year as one of the league’s best teams against four-seam fastballs. Lately, that narrative has flipped.

In March/April, the Diamondbacks hit .276 with a .442 slugging percentage on four-seamers, which ranked third and sixth in baseball, respectively. In May, their batting average against heaters has decreased to .233 (19th) and their slugging percentage has decreased to .387 (22nd).

Interestingly, D-backs hitters have actually seen very little drop-off in production against four-seamers below 95 mph this month. The drop-off against four-seamers at or above 95 mph, however, has been enormous:

For the season, the Diamondbacks still have strong numbers against fastballs below 95 mph, but their numbers against fastballs at 95-plus are now below-average.

Of course, production in these velocity ranges varies significantly by player. Here is a look at how each D-backs hitter has fared against four-seamers below 95 mph versus heaters at 95-plus:

(To keep things simple, we are using the all-encompassing hitting metric, weighted on-base average, or wOBA, to compare.)

A few things stand out here:

• The Diamondbacks’ wOBA against fastballs below 95 mph is 113 points higher than their wOBA against fastballs at 95-plus. That difference is about twice as much as the league average.
• Joc Pederson haș produced exceptionally well against fastballs in both velocity ranges.
• Corbin Carroll has struggled mightily against fastballs in both velocity ranges, with basically no difference between the two categories.
• Eugenio Suárez has been slightly above average in the below-95-mph bracket (.379 wOBA) but had almost no success against fastballs in the 95-plus bracket (.143 wOBA).
• Suárez, Christian Walker and Gabriel Moreno have all been above average against fastballs below 95 mph but below average in the 95-plus bracket.
• Lourdes Gurriel Jr. has been below-average in both brackets.

Of course, just because a hitter is struggling against four-seamers above 95 mph is not necessarily alarming. Perhaps they always have, and they found other ways to make up for it.

To find out, we can compare each hitter’s numbers against hard four-seamers this year with their numbers last year. As shown here, four D-backs hitters have seen significant drop-offs (more than 100 wOBA points) against fastballs at 95-plus:

On the surface, these differences are pretty alarming.

Of course, the season is still only about two months old at this point. There is plenty of time for these narratives to flip. For now, all we can say for sure is that the Diamondbacks will need to be better against velocity to get back on track.

Poor swing decisions

Hitting, of course, is not only about putting the ball in play. It is also about laying off tough pitches, and finding other ways to get on base.

In March/April, the Diamondbacks had the sixth-highest walk rate in the league at 9.6 percent, building on a recent trend. The Diamondbacks had better-than-average walk rates in both 2022 and 2023 as well.

May, however, has been a different story. The Diamondbacks’ walk rate this month is just 7.3 percent, which is tied for 25th in the league.

Their walk totals have been particularly low over the past couple of weeks. The Diamondbacks have drawn three or fewer in eight of their past nine games, and they are averaging just two walks per game over the past 14 contests.

Typically, drawing fewer walks is a symptom of chasing more pitches out of the zone. Sure enough, that has been the case for the D-backs.

In the month of May, D-backs hitters have chased 28.4 percent of pitches out of the zone, up from 26.2 percent in March/April. League average is 28.2 percent. Last year, the D-backs’ had the eighth-lowest chase rate in the league at 26.6 percent.

This month’s 28.4 percent mark is the team’s highest in any month since July of last year, when they swung at 29.3 percent of pitches out of the zone. It is no coincidence that July was also the team’s worst month in 2023, with a record of 8-16.

Laying off a few more pitches, of course, will not necessarily put more runs on the board. But, based on how this offense has fared in the past, it is probably a good place to start.

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Top photo: Katie Stratman/USA TODAY Sports