At long last, a D-back rode the bullpen cart -- the team's newest reliever, Brad Ziegler

Before the start of the 2018 season, the D-backs dropped some news: They'd have a bullpen cart for use at Chase Field for home games. A real, live (OK, not live) bullpen cart, complete with D-backs coloring, a motor, a driver, the whole bit. 
Several pitchers enjoyed a casual ride in to the mound as the season rolled along, among them the Astros' Collin McHugh (the first passenger), the Nationals' Sean Doolittle (the second), and so on.
On June 1, then-Marlins reliever Brad Ziegler took a ride as well: 

Here’s Brad Ziegler’s (@BradZiegler) entrance in the #DBacks bullpen cart. #Marlins pic.twitter.com/2Gg3xkL1y4

— Glenn Geffner (@GlennGeffner) June 2, 2018

Are you realizing the trend, though? Every pitcher listed above was not a D-back. Until this week, no Arizona reliever used the cart. It was only members of the opposition who took the team up on the offer.
That changed, technically, when Jake Diekmanenjoyed a jaunt over from the visiting dugout after his trade from the Rangers to the D-backs on July 31. 
But now all of that is in the past, as a real, actual D-back used the cart ... Ziegler, who obviously enjoyed it so much the first time around with Miami that he felt compelled to do so for his 2018 Arizona debut in Thursday night's 8-1 loss to the Giants: 

View this post on Instagram

History. Brad Ziegler became the first #Dbacks pitcher to catch a ride in the OnTrac Bullpen Cart. #GettingZiggyWithIt

A post shared by Arizona Diamondbacks (@dbacks) on Aug 2, 2018 at 9:14pm PDT

History, indeed.