Paul Maholm was recently named the most underhyped player in baseball. Perusing his opposing batter history on Baseball Reference, I could see why some would think he was underhyped. Prince Fielder has a .071/.152/.071 line against Maholm in 46 career plate appearances. On the other hand, Bill Hall, sporting a .581/.639/1.032 clip in 36 PAs, probably doesn't really see what all the fuss is about. So who would you rather have against Paul Maholm?

Going by The Book, first we look at career numbers to get the largest possible sample. Better yet, we can look at a projection system, which distills those career numbers, adjusts them for age and weighs them by season. ZiPS projects Fielder at a .401 wOBA and Hall at a .302 wOBA. Fielder is a superstar while Hall is a utility man. We've got that out of the way. So how to explain the Maholm divide?

The Book says to next look at platoon splits. Fittingly, Hall and Fielder have identical .348 wOBAs against southpaws. Furthermore, Maholm has a massive career platoon difference of 100 points in wOBA. That closes the gap, and that's about as far as The Book goes. To get the rest of the way there, I thought PITCHf/x might come in handy, so using movement, velocity, and location as my inputs against LHPs, I tried to predict their success against Maholm's offerings.

Maholm throws both his two-seam and four-seam fastballs around 88-90 miles per hour, and throws them on just over half of his pitches. His two-seamer has better movement in my opinion, and has certainly achieved better results, yet interestingly, he throws it less often to same-handed hitters. I'm not sure this is a wise move overall—he might be handicapped by wanting to throw his two-seamer only to his arm side—but against Prince Fielder, his choice of fastball has certainly paid off. I grabbed 1,000 fastballs against Fielder from LHPs and plotted Fielder's success (RV100) by pitch movement. I also added lines to indicate the average movement of Maholm's two fastballs.

Fielder is above average on risers but below average on sinkers. Movement is not the only reason that Maholm's four-seam fastball stifles Fielder. The location of Maholm's four-seamers also coincides with Fielder's weakness

In fact, Fielder has swung at 23 Maholm four-seamers. All but five he has either fouled off or swung through. As for the five he put into play, all of them were grounders, and only one was a single. Two were double plays. So to sum up, Maholm uses his four-seam fastball a lot facing lefties, and it just so happens that said fastball matches up perfectly against Fielder.

Furthermore, Maholm's slider, his best pitch, is death on Fielder, and LHBs in general. However, Maholm only uses his slider 7% of the time against righties. Instead, he takes the changeup out of his pocket and also uses the curve a bit more. But his changeup isn't as good a pitch as his slider, even when accounting for the platoon differential. And against Hall, Maholm's choice of off-speed pitches is asking for trouble.

Maholm's changeup comes in at 83, his slider at 80, and his curve at 73, and they follow the PITCHf/x spectrum of movement. His changeup is in the top-right quadrant, dropping the least out of his off-speed pitches and moving the most toward his arm side. His slider is right near the origin, with average values of 0 inches in horizontal and vertical movement. And his curveball is diametrically opposed opposed from his changeup, as it breaks down and in towards righties. Conventional wisdom and PITCHf/x analysis both say that the slider has the largest platoon split of all off-speed pitches, so perhaps Maholm is right to scrap it against righties. But Hall apparently isn't a normal righty. Against off-speed pitches, here is how he does based on horizontal and vertical movement:

The troughs in both charts appear in the areas where Maholm throws his slider. This means that sliders might be the best pitch to throw Hall. There's room inside to throw the slider, and he's also willing to chase them in the dirt when LHPs try to backfoot him. But Hall destroys offspeed pitches left out in the zone.

Hall has been thrown twelve curves from Maholm. He swung at three of them, connecting for two singles and a double. He was also hit by one of them, and most of the rest went for balls. Hall's put four changeups into play, good for a groundout, a single, a double, and a home run. Again, most of the rest were balls.

Prince Fielder is soon to sign a contract worth over $100 million, while Bill Hall might be out of baseball in a year. Yet in certain contexts, Hall might be the better player. Given both batter's substantial platoon split, and more importantly the large platoon split of Paul Maholm, you could project Fielder and Hall to hit Maholm equally. And digging deeper, it is evident that Maholm's strengths match Fielder's weaknesses and Maholm's weaknesses match Hall's strengths. The case can be legitimately made that Bill Hall projects to be a better hitter than Prince Fielder against Paul Maholm.