Still just 19-years old, the Dominican Republic native has seen his workload increase each season.
"I signed four years ago and felt very good at the workout but don't remember much," Pimentel admitted through a translator. "I remember being extremely happy."
Last year was the first time he was used more extensively as a starter, logging seven of his eight career starts. He found success down that road, despite a 1-2 record.
In 32.1 innings as a starter, Pimentel posted a 2.78 ERA and held the opposition to a .209 average. He went 2-2 with a 5.19 ERA over 12 relief appearances.
Ironically, Pimentel actually prefers the bullpen.
"I don't know where I will be pitching when the season starts but I have been working out of the bullpen," he said of his time in Arizona. "I like working out as a relief pitcher. The difference is a starter has to pitch for one day and then rest for five days. In the bullpen I am more comfortable and get to pitch more. I have to always be in shape."
He throws a fastball, slider and added a changeup to his repertoire this year. The heater comes in at 92-93, although he was working at 89-90 MPH in extended spring training.
His favorite pitch is his slider, a pitch he feels comfortable throwing ahead in the count to notch strikeouts. Last year, when he fanned 54 in 49.2 innings, he was able to bury the pitch and get hitters chasing.
Since coming to the states, he has noticed some differences.
"Everyone is smart here with their pitching and it is a better competition level overall," Pimentel admitted.
But, he feels he is ahead of the game because of his three years of experience in the DSL. Instead of learning the nuances of the game, Pimentel feels he is a smarter pitcher with the intelligence to throw his pitches in off-counts to keep the hitters guessing.
He does, however, have things to improve upon.
"I am working on my mechanics and improving my four-seam fastball," Pimentel said. "I am trying to stay closed a little bit better."
One of the concerns for him is the 66 walks he has issued in 117.2 career innings. He feels he has made strides in that area and knows his stuff is good enough to get outs even if they manage to hit the ball.
The focus, therefore, has been on first-pitch strikes since coming to Arizona and he is pleased with the results.
"I have been controlling my first pitch very well," said Pimentel.
Now, he is poised to make his stateside debut this year and hopes the three years in the DSL gives him further success this season.