With deserved nods to the likes of Justin Turner and Anthony Rendon, the debate over "best third baseman in the National League" probably comes down to Kris Bryant of the Cubs versus Nolan Arenado of the Rockies. As with any such sports discourse, things tend to break along partisan lines -- Cubs rooters will stump for Bryant, while right-wise Coloradans will fly the Arenado flag. Let us, however, take a more dispassionate view of the Bryan-Arenado faceoff. Such an approach is necessary because, well, it's complicated ...

The matter of WAR

Wins Above Replacement (WAR) is something of a blunt instrument, but it's a necessary one when trying to assess a player's overall value, as it hangs a number on everything a player does on the baseball field. Because nothing can be simple, we've got three versions of WAR in the public sphere: the Baseball-Reference version (bWAR), the FanGraphs version (fWAR), and the Baseball Prospectus version (which is abbreviated as WARP). While they all use different means to arrive at the final number, all take into account, for position players, hitting, baserunning, and defense. As well, all adjust for positional value (e.g., a shortstop is worth more than a first baseman of similar offensive outputs) and attempt to correct for the influences of a player's home ballpark.

With regard to Bryant and Arenado, let's see how the three versions of WAR rate them in 2017 and then on a cumulative basis for their three overlapping seasons in the majors (2015-17) ...

Player/WAR type bWAR fWAR WARP Arenado in 2017 7.2 5.6 6.8 Bryant in 2017 6.1 6.7 6.6 Arenado from 2015-17 19.5 15.6 22.0 Bryant from 2015-17 19.7 21.5 21.5



So that's a mixed bag. FanGraphs sees Bryant as being superior over the last three seasons by a significant margin, while Baseball-Reference and Baseball Prospectus see them as being pretty much identical players in terms of overall value. So what's going on with the FanGraphs evaluations? Part of it is that it rightly sees Bryant as the better baserunner. Bryant's got deceptive speed, and even though he's not a volume base-stealer, he uses that speed to add value. For instance, Bryant is one of baseball's best when it comes to staying out of the double play, and over the last three seasons he's taken the extra base 54 percent of the time to Arenado's 44 percent.

As well, Bryant in 2016 enjoyed a big jump in terms of his defensive value, at least when it comes to how FanGraphs measures it. In 2015 and 2017, FanGraphs measured Bryant as being, respectively, 7.1 and 2.3 runs better than replacement level with the glove. In 2016, however, that figure spiked to 11 runs. Overall, Bryant's probably a plus fielder at third (and at other positions), but single-year defensive measures are prone to noise and randomness. FanGraphs sees Arenado as the better glove over the last three seasons, but it's fairly close. Baseball-Reference and Baseball Prospectus, meantime, see Arenado as being better than Bryant on defense by a wide margin.

With that, it's probably time to talk about the ballparks ...

The Coors effect

Arenado as you know plays his home games at a mile above sea level, and the thin air of Denver benefits the hitter to extremes. That's been the case even in the post-2001 humidor era.

If you look at the two players' unadjusted batting lines over the last three years -- .288/.388/.527 for Bryant and .297/.353/.577 for Arenado -- you might give the edge to Arenado based on his power advantage. However, you can't make such straight comparisons, especially when one of the two players calls Coors Field home. In the case of Bryant and Arenado, each is a right-handed batter. Here's how their home parks have affected run production for right-handed hitters since the start of the 2015 season (park factors via Baseball Prospectus) ...

Coors Field: +15.7 percent for RHBs

Wrigley Field: +2.7 percent for RHBs

Each is a good environment for right-handed batters, but Coors, as you would expect, is on another level entirely. You must adjust for that. Speaking of which, in terms of park-adjusted OPS (OPS+) Bryant comes out well ahead of Arenado. Over the last three seasons, Bryant has an OPS+ of 142, which means his OPS on a park-adjusted basis has been 42 percent better than the league average. Arenado, meantime, checks in at 128. That's an excellent figure, but it's well shy of Bryant's.

At this point, though, we get into the unknown. There's some evidence that the peculiar nature of Coors Field results in a "hangover effect" when Rockies hitters head out on the road. In other words, Arenado may be working against factors that don't apply to Bryant, factors that make it more difficult for him to hit closer to sea level. We don't have the means to adjust for that right now, largely because it's an unknown, but we should be mindful of the possibility as we compare the two players.

Of note, then, is how the players have fared in road games since 2015 ...

Arenado in road games, 2015-17: .273/.331/.521 (1,025 plate appearances)

Bryant in road games, 2015-17: .293/.387/.501 (1,020 plate appearances)

Bryant's been better in road games thanks to the big edge in OBP, but it's closer than you might have guessed. If Arenado is indeed working against factors that we can't account for, then it's even closer. Part of drawing distinctions between two great and similar players is acknowledging that we can't know everything we want to know. The extent to which playing home games in Coors Field affects one's ability to produce on the road is one of those gray areas.

Clutch considerations

"Clutch performances exist but clutch players do not," is a bit counterintuition that holds a lot of truth. You'll see wide swings in a hitter's production in clutch situations, but it doesn't add up to any kind of sustainable skills. Good hitters will, over time and given a large enough sample, tend to be good in all situations, and bad hitters, over time and given a large enough sample, will do the opposite.

That said, performance in high-leverage situations is a value thing to look at when assessing a player's value in the past, so let's do that here ...

Player/Stat, 2015-17 Overall OPS OPS w/ runners on OPS w/RISP OPS in high-leverage spots Arenado .930 1.064 1.214 .985 Bryant .915 .943 .861 .685



This is all in Arenado's favor, especially when it comes to producing in critical game situations. His production increases significantly in all three splits, while Bryant's has decreased with RISP and in high-leverage spots -- precipitously so, in the latter instance. With Bryant, we're talking about a sample of 209 high-leverage plate appearances in his career, so don't take this to mean anything going forward.

This, after all, is a player who cleanly fielded one of the most high-pressure ground balls in MLB history ...

In terms of backward-looking value assessments, though, Arenado's come up bigger than Bryant in big spots. Over at FanGraphs, they undertake a deeper dive into clutch performance with their "Clutch" metric. Clutch, in the site's own words, measures "how much better or worse a player does in high leverage situations than he would have done in a context neutral environment."

Here's how the two players shake out since 2015 ...

Arenado: +0.88

Bryant: -3.26

It bears repeating that this doesn't mean anything when we think about who's going to be better in the future, but it is relevant to our evaluations of past value.

This hasn't been intended to provide clarity or even a soft answer. I'd probably take Bryant over Arenado if the sole consideration was the future, in large part because he's roughly nine months younger. Just as there's no obvious answer there, though, there's also no obvious answer when it comes to who's been better over their shared mini-era. Besides, starting arguments is more fun than finishing them. I dunno, man. Gotta run.