A 16th-round Cubs pick in the 2004 draft from Western Michigan, Mathes had been on cruise control throughout the Cubs' farm system, advancing to Triple-A by only his third full season of pro ball and without so much as a hitch really.
He has won 31 games over the last three years, including 10 this past season at Class AAA Iowa, where he logged 151 2/3 innings with a 5.58 ERA.
That was a far cry from a year ago, when Mathes was a Southern League (Class AA) All-Star with a 3.27 ERA.
But if the 25-year-old left-hander is bothered by his 2007 campaign, he masks it well.
When asked to review his season, Mathes acknowledged that the numbers were not to his liking, but he insisted that it was still a "good year."
"I felt like it was a good year because it was one where I struggled a bit," he said, reasoning, "I haven't really struggled all too much in my career, so it was kind of a test for me. I feel pretty comfortable about it actually."
It was a year filled as much with learning as it was with struggles.
Mathes learned that Triple-A (particularly the Pacific Coast League), for instance, is not the pitcher's best friend. The ballparks are more hitter-friendly than any in the Southern League.
Mathes also learned that overthrowing the ball can lead to trouble.
"At some times, I would throw too hard and the ball would be up in the zone a little bit," Mathes said. "My pitching coach (Mike Harkey) said, ‘Try to take some off a little here and there and keep the ball down in the zone.'
"From the middle of the year toward the end, my fastball was 87 (mph) and I'd (top out at) 91. It would go up, but I would sacrifice some movement and some location. I have to make sure I keep the ball down in the zone."
Mathes features a four- and two-seam fastball in his repertoire, plus a changeup and curveball. His work with those pitches involved "a little bit of everything," he said.
"My changeup was hit and miss this year, same with my breaking ball," Mathes said. "It was a constant battle for me all year just to feel like I had everything locked in like I should have."
But it wasn't necessarily a disappointment, said Mathes, who was in plenty of good company with struggling pitchers in the PCL this season.
Only one club (Nashville) in the 16-team league finished with a combined staff ERA below four points. The average ERA of a PCL pitcher was 4.68.
"At the end of the year, when I looked at some of the numbers that other pitchers put up, I felt like I was up there within the mix of some of the top prospects from other organizations, so I didn't feel too bad about it," Mathes said.
"From what I was told by a lot of other pitchers on our team, if you can pitch in the PCL, you can pitch pretty much anywhere."
Mathes put together enough good starts to prove that he can pitch in the PCL, but he will need more consistent results there if he's able to move past that level.
It seems likely that he'll be back in Triple-A next season, although he'd like to make one particular stop before then.
Despite logging more innings than anyone on the Iowa staff, Mathes hasn't stopped throwing now that the minor league season has ended, and he would like to spend some of his off-season in a Winter Baseball League in Venezuela.
Should he pitch there, he would like to give the bullpen a try.
"I've been a starter pretty much my whole career, so I feel if I went and played winter ball and showed that maybe I could come out of the ‘pen, it might open some eyes," said Mathes. "Maybe someone will say, ‘Well, he's good out of the ‘pen. He gets lefties.' So it's something that I might as well give a chance and see if it works out.
"It's not really a tryout, but more like applying for a job."