Scottsdale, Ariz. — As far as the Tigers are concerned, one of the biggest success stories of this Arizona Fall League season has been right-hander Montreal Robertson.

“He’s a good story,” said Tigers minor league pitching coordinator A.J. Sager.

Robertson, a 6-4, 205-pounder whose fastball is hitting 97 mph, has allowed just two runs and six hits in 82/3 innings this fall. His WHIP is 0.69 and he’s struck out six with no walks. This from a guy who was stunned speechless when he got the call that he’d been invited to play in the league, which showcases the top prospects in baseball.

“I am so blessed,” he said. “I didn’t see that one coming. But it’s a great feeling when things start to click a little bit.”

A 29th-round draft pick of the Tigers in 2011 out of Coahoma Community College in Clarksdale, Mississippi, Robertson came with a high-90 mph fastball and little else. He floundered through rookie ball, Low A and High A for three years, unable to command any other pitch but his fastball.

“When I got to pro ball I had a lot of things I had to work on to repeat my delivery and get command,” said Robertson, an unfailingly polite and introspective 25-year-old. “Command was the thing that always hurt me the most. I didn’t have it. I couldn’t throw my off-speed for a strike.

“You are going to have a slow progression when you can’t do those things.”

From 2011 through 2013, from rookie ball to Low A at Connecticut and West Michigan, briefly to High A Lakeland, then back to West Michigan, Robertson walked 77 in 1562/3 innings. But he was undeterred.

Former Tigers closer and minor league coach Mike Henneman taught him a split-fingered fastball and today it is his best secondary pitch. He’s also developed a slider-curve pitch (a slurve) that he uses as his off-speed.

As he’s become comfortable with those two pitches, consistently throwing them in the strike zone, his stock has rapidly risen. In 2014 at West Michigan, he walked 28 in 751/3 innings with 59 strikeouts.

It came together for real this past season. He posted a 3.31 ERA at Lakeland and Erie, with 35 walks and 58 strikeouts in 68 innings.

“Last year was the first time when I got into jams I was able to get out of them by pitching,” Robertson said. “Not just trying to blow guys away but being able to locate my off-speed and spot my fastball. It’s a great feeling when you aren’t walking guys every outing.”

His pitch-ability was on full display Monday. Playing against the team from Surprise, which features prospects from the Royals, Cardinals, Rangers, Yankees and Brewers, Robertson pitched scoreless sixth and seventh innings.

He gave up two singles to start the sixth, one to the Rangers’ Jurickson Profar. But he was unfazed. His reaction to that situation was what the Tigers are looking for — he found a way to pitch his way out of trouble, not just rare back and throw.

“I just tried to calm down,” he said. “I got runners on, but a ground ball gets two outs and that changes everything.”

He fell behind 3-1 to Yankees designated hitter Gary Sanchez, but came back to strike him out with a fastball and splitter. He struck out Yankees outfielder Tyler Austin with a slurve and got the Royals’ Bubba Starling, the fifth overall pick in 2011, to fly out routinely to left on another well-placed slurve.

“I wasn’t necessarily trying to strike the guys out,” he said. “I was trying to make my pitches and make them get weak contact — just playing the odds.”

That mature approach has been hard-earned.

“It kind of proves the point,” Sager said. “It’s always been the case, but we sometimes forget, for some guys it takes a little while to put the package together. We are all guilty of wanting guys to show up and be big-league ready real quick. That doesn’t always happen.

“Some guys do it more step by step. I think in some regards, that’s good, too. He has faced adversity and he’s come through it. He’s done a lot of things that will serve him well whatever the highest level it is he achieves.”

Robertson could begin the 2016 season at Double A Erie, but he is making a push for Triple A Toledo.

“I would be more than ready for Toledo,” he said with a smile. “I’m not going to say I’m prepared, but I am preparing myself for that.”

Toward that end, he is trying to develop a straight changeup.

“I need something I can command better when I need a strike, something other than my slider-curve,” he said. “I like my split-finger, I will never stop throwing it. But I think I need a changeup that I can throw more consistently for strikes.”

One cautionary note: Robertson had Tommy John surgery in 2009. Former Tigers closers Joe Nathan and Joakim Soria both had to have second Tommy John surgeries five years after they had their first.

Even transplanted ligaments wear out. This will be Robertson’s seventh season, post-surgery.

But that’s the last thing on his mind right now.

“I just want to be the guy you can call on when things are getting tough out there,” he said. “It’s always tough out there, but I want to be a guy that can be counted on in late innings with the game on the line. I would love to be that guy and I will just keep working to be that guy.”