The thing about professional sports, though, is that it doesn't matter what a player believes or what you want to believe. It matters what the decision-makers believe, what the guys with the radar guns and videotape and watchful eyes believe. It matters what the swings of opposing hitters tell the pitching coaches to believe, what their years of major league experience have conditioned them to believe.
Over the next 6 weeks, Mathieson will be one part pitcher and one part proselytizer, espousing his gospel through the splitters and the sliders that he has worked hard to refine.
He spent the majority of last season dominating the competition at Triple A Lehigh Valley, saving 26 games with a 2.80 ERA and 83 strikeouts in 64 1/3 innings. It was his first full season since 2006, when he earned a promotion to the majors as a 22-year-old starter, back before his elbow broke down and sent him on a 3-year journey to full health. Mathieson had just one appearance in each of the two occasions the Phillies called him up last season, allowing three baserunners and two runs in one outing, and four baserunners and one run in the other.
Ten days from now, he will turn 27 years old, an age at which most professional athletes have already determined their future. Mathieson's future, according to the men who determine such things, rests on his ability to throw his secondary pitches, the offspeed stuff that can offset a blazing fastball that sends radar readings into the upper 90s.
"At the major league level, fastballs are not enough, no matter how hard you throw," said assistant general manager Chuck Lamar, who oversees the Phillies' minor league prospects. "He needs to develop a secondary pitch. His slider is improving, but still not where he or we would want it to be."
Which brings us to Mathieson's new pet project.
In the long history of human beings throwing hard objects for material gain, the split-fingered fastball is about as antithetical as it gets. Instead of optimizing the hand's ability to put pressure on the ball, a pitcher grips the surface between his index and middle fingers. The biggest key, though, is in the delivery, which concludes with a downward pull on the ball during its release. When thrown correctly, the pitch approaches the plate like a fastball before taking a sharp dip downward. It is a difficult pitch to hit, and it is a difficult pitch to master.
With that in mind, the Phillies enlisted the guidance of Hall of Famer Bruce Sutter to help introduce the pitch to Mathieson in the fall.
"We felt like mechanically" the pitch would fit Mathieson, Lamar said, "because of his over-the-top type of arm action, to be able to pull down on that splitter. He's got big hands that fit that pitch, at least the guys who have historically thrown it well. And he's a high-fastball pitcher for the most part. So that splitter, something going down, would change the eye level of the hitters and really fits what he's trying to do . . . Whether he can adjust to it or not is yet to be seen."
Sutter, who used the splitter to build a 12-year career that included the 1979 National League Cy Young, spent his first few sessions talking and playing catch with Mathieson.
"We actually didn't throw a bullpen until 4 or 5 days in," Mathieson said.
Although it took him a while to get a feel for the splitter, he is optimistic that it will become a major league pitch for him. In his first bullpen session of the spring, he threw it six or seven times.
That said, Mathieson isn't giving up on his slider.
"I still believe in my slider," he said. "I'm going to throw it until the day I'm done baseball."
But do the Phillies share his faith?
"We're not sure which way, really, still," pitching coach Rich Dubee said. "He needs something of consistency, and we don't know which one is going to have more consistency, whether it be the splitter or the slider."
Which is why Mathieson knows what he has to do this spring.
"I'm going to make them believe it," he said. "I need to prove it." *
For more Phillies coverage and opinion, read David Murphy's blog, High Cheese, at www.philly.com/HighCheese. Follow him on Twitter at