"He is a guy who looked after me and helped me a lot," Faulkner said. "He is a great guy and a great teammate."
Because of that, Faulkner admitted it's a "hard" situation that he finds himself in going into Spring Training. Diekman had surgery last month to have his colon removed and ease the constant discomfort he was dealing with from ulcerative colitis. He is expected to be out for at least the first half of the season, so the Rangers will have to find a replacement for their primary left-handed setup reliever.
Faulkner, who was at the Rangers caravan stop Thursday night and is headed to Arizona next week, is one of several left-handers who will be given a chance to fill the void left by Diekman's absence.
"I just have to look at it and make sure I'm ready," Faulkner. "Going out to Arizona early is a good start."
Faulkner knows he will be watched carefully along with fellow left-handers Dario Alvarez and Wesley Wright. The Rangers need at least one of them to claim a job and provide some balance with established left-hander Alex Claudio in a bullpen heavy on hard-throwing right-handers.
"Coming into it, I know I have to prove myself and I'm going to throw more innings than most other guys," Faulkner said. "I have to mentally prepare myself and be ready."
Faulkner was tremendous in Arizona last year. He pitched in eight Cactus League games and allowed one run on five hits and three walks with eight strikeouts. He made the Opening Day roster as the second left-hander in the bullpen, but once the Rangers went to Texas, everything changed.
Faulkner allowed five runs in the last exhibition game and then four runs through his first five regular-season games. He was optioned to Triple-A Round Rock, called up for three appearances in May and then not seen again until late September.
"I struggled a little bit early. ... It was tough," Faulkner said. "It was a really good learning experience. It stinks being optioned back and forth but everything happens for a reason. I look at the positives and learn from it."
The main thing he needs to learn is to command the fastball and keep his breaking pitches down. If he does that, he could be a dominating reliever. The breaking ball has been a point of emphasis in his winter workouts.
Faulkner and Diekman are both hard-throwing left-handers with fastballs that average 92 to 95 miles per hour. The difference is Diekman has the wipeout slider.
Diekman and Faulkner both threw their slider 25 percent of the time last season. But Diekman had an overall whiff rate of 54.6 percent on the sliders he threw while Faulkner's was 8.3.
"You leave a ball up in the zone, it's going to get hit ... especially if it's not breaking," Faulkner said.
That's why Diekman was so important to the Rangers and why he is going to be hard to replace. Faulkner hated to see his friend and teammate go down but the Rangers haven't forgotten what Faulkner did last spring.
If Faulkner can master the breaking ball, he could be exactly what the Rangers need to replace Diekman.