The parallels between Ryan McMahon and Nolan Arenado are easy to spot. After all, both were high school third basemen from California taken in the second round, both have shown the ability to be great defensively (the 39 errors McMahon made in 2015 will give pause, but they don't give a full indication of potential), and both immediately hit well in their professional careers -- and kept hitting well as they moved up the minor league ladder.
In his first two pro seasons, the lefty-swinging (okay, that's different from Nolan) McMahon excelled against pitchers that were on average 2.5 years older than him, posting a 147 wRC+ at Rookie-ball Grand Junction and 137 wRC+ at Low-A Asheville. On defense, he was marked as the top defender at the position in the South Atlantic League by multiple scouts. Sure, McMahon made 44 errors over his first two seasons, but those errors had a lot to do with context (and some erratic throws); we're talking poorly groomed infields and first basemen who don't have the digging skills possessed by major leaguers.
Those hitting performances at his age and the defensive potential put McMahon on the very edge of preseason top 100 prospect lists heading into 2015. After a stellar performance by the just turned 21-year-old in 2015 in the High-A California League, McMahon has elevated his prospect stock solidly into that top 100 group. He recently placed 36th on the Baseball Prospectus top 101 list for 2016, 48th on MLB.com's top 100 for 2016 (and was ranked as the third-best third base prospect), and 57th in Minor League Ball's mid-season 2015 update.
Here's what the scouts had to say:
Baseball Prospectus (101 List)
You can nitpick McMahon's performance the last two seasons if you like. In 2014 he played his home games in Asheville, which has one of the most inviting right-field porches in minor-league baseball. And in 2015 he played all of his games in the Cal League, which is the Cal League. There is 20-home run power in his bat in any park or league, though, and McMahon is a polished third baseman with a plus arm, so he will contribute on the defensive side as well. Perhaps someday he'll do enough to please you.
MLB.com (Top 100)
While it's true that McMahon benefited from excellent hitting environments, he produced everywhere he went in his first three pro seasons, batting a combined .297/.372/.524 and leading the high Class A California League with 43 doubles last year. He has a smooth left-handed swing with bat speed and loft, generating power to all fields. McMahon also shows good feel for hitting and the patience to take walks, and he could hit for a solid average if he makes adjustments and cuts down on his strikeouts.
McMahon has the tools to be an asset at the hot corner, but he is an erratic defender who has led his league in errors by a third baseman in each of the past two years, including 39 in 2015. A good athlete with solid arm strength and reliable hands, he gets into trouble with his footwork.
In a mid-year 2015 evaluation, Wilson Karaman of BPro gave McMahon 55 or better tool scores across the board, with the exception of speed, for an overall OFP of 60 and a realistic role of a first-division regular. Here was his conclusion:
McMahon is a solid across-the-board prospect without any glaring holes in his projection. He's among the younger regular position players in the California League, and while his swing and approach are both still works in progress, he's held his own thanks to impressive athleticism and a broad foundation of skills. It'll require some seasoning, but there's an above-average hit/game power bat here, and with a frame capable of adding additional mass, an outside chance for an actualized 55/60 hit/game power hitter at the hot corner. Coupled with above-average defensive projection he has the tools and talent to develop into a first-division major leaguer.
To recap his 2015: in 556 plate appearances with Modesto (again against pitchers 2.5 years older than him), McMahon produced a .300/.372/.520 line (141 wRC+) with 67 extra-base hits. That line is inflated somewhat by a .401 BABIP, but it's nonetheless impressive given the context. McMahon had an acceptable 8.8 percent walk rate given his power production, though he struck out more often than I'd like to see (27.5 percent). McMahon was even hotter in the season's second half, putting up a .308/.363/.563 line with 35 extra-base hits in 247 at-bats. He also managed a respectable .290/.380/.484 line in 124 at-bats against left-handed pitching, a weakness for him at Asheville last year.
McMahon's professional career to date has been everything we could have hoped for and the reports about his makeup are just as encouraging. And oh by the way, McMahon (who signed for just over $1.3 million) is still pretty raw as a prospect after spending his high school days splitting time between baseball and quarterbacking (sound familiar?), so we could see even more growth from the lefty as he moves up the organizational ladder.
I placed McMahon fifth on my ballot given his performance, draft position, and plus tools. Actually, it's a little ridiculous that a prospect of his caliber is only fifth in the system. McMahon should start next year in Double-A and will have the opportunity to prove that he can continue to mash even against upper-level pitching. After that? Currently there's an Arenado impediment between McMahon and the starting third base job, but I think the latter could end up contributing at either corner infield position or even as a corner outfielder if the former is still in place by 2018 or so.