Nick Piecoro

azcentral sports

In his second start with his new team on Saturday, New York Yankees right-hander Brandon McCarthy fired six innings of one-run ball against the Cincinnati Reds. As it pertains to the Diamondbacks, it isn't just the results that are of interest, it's how he said he accomplished them.

McCarthy, who was traded to the Yankees on July 6, used his cut fastball with increased frequency, telling reporters the Diamondbacks had discouraged him from throwing it. Yankees General Manager Brian Cashman told the New York Daily News his analytics department believed McCarthy could have more success by reincorporating the pitch into his repertoire.

Before going any further: McCarthy was a model of inconsistency during his 1½ seasons with the Diamondbacks. He has made just two starts with the Yankees. It's too soon to read too much into it. Still, it's hard not to view it in the context of the Diamondbacks' recent pitching deficiencies.

McCarthy's success falls in line with a troubling trend: Pitchers who leave Arizona tend to improve, those who arrive here often regress, and the Diamondbacks can't seem to turn around those who are struggling.

Diamondbacks General Manager Kevin Towers said the Diamondbacks didn't take the cutter away from McCarthy. They just wanted his sinker to be a more prominent weapon.

"I just think when he was in Oakland, he was a guy with heavy sink who got ground balls," Towers said. "That was his bread-and-butter pitch. We just wanted to get him back."

Pitch-f/x data available at BrooksBaseball.net, however, indicates the cutter was a significant part of McCarthy's repertoire in Oakland. He threw it 41 percent of the time — more often than his sinker (36 percent) — and with good success.

And while it's true the cutter wasn't a particularly effective pitch during his time with the Diamondbacks (opponents hit .279 off it), it was better than his two-seamer (.316).

McCarthy isn't the only pitcher the Diamondbacks couldn't salvage. Among Ian Kennedy, Tyler Skaggs and Trevor Bauer, none has become a dominant major-league starter with his new club, but all are pitching better — and throwing harder — since leaving. What went wrong while they were here?

Like McCarthy, right-handers Trevor Cahill, Randall Delgado and Addison Reed all joined the Diamondbacks and have had their results suffer.

Since the start of 2011, the list of pitchers who improved upon coming to the Diamondbacks is short and riddled with asterisks.

Right-hander Brad Ziegler has been equally effective here as he was in Oakland. Relievers David Hernandez and Matt Reynolds have had success, but both wound up needing Tommy John surgery, which raises another concern.

In the past five years, the Diamondbacks have had eight pitchers need Tommy John surgery, tying them for the most in the majors. Even the unbreakable Bronson Arroyo wound up getting hurt.

Reliever Oliver Perez might be the best example of a pitcher the Diamondbacks brought in who has both pitched well and stayed healthy.

Are the Diamondbacks acquiring and/or trading away the wrong pitchers? Is it their coaches? Is it the pitch-calling?

"It's not anything that we're doing in the minor leagues or development or up here that prevents guys from having success," Towers said. "Especially young guys, they usually get better with time and experience in the big leagues. The reason why guys get better (elsewhere) isn't because we don't have good instructors here. I believe in our staff and in our farm system and the people we have down there."

Maybe this is all just bad luck and unfortunate timing for the Diamondbacks.

It's worth noting that pitching at Chase Field is no easy task. Maybe those pitchers were bound to get hurt. Maybe McCarthy, Kennedy and Skaggs were bound to pitch better, regardless of team, and their subsequent success shouldn't be an indictment on the organization or its processes.

But even that line of thinking has a counterargument: If they were bound to improve, shouldn't the Diamondbacks have held onto them and either enjoyed their success or traded them for more later?

These are difficult questions, but they're also within the purview of a team with the second-worst ERA in the league. In the name of improvement, the Diamondbacks need to be asking them.

Reach Piecoro at 602-444-8680 or nick.piecoro@arizonarepublic.com. Follow him on Twitter @nickpiecoro.