Nolan Arenado's combination of on-base ability, run creation, total value amounts to a rare season

A few days ago, Ryan Spilborghs—famed grand slammer and current member of the Colorado Rockies’ ROOT broadcast team—tweeted a conversation starter:

Can someone please explain how Nolan has a 4.1 war?See if list shocks you as much as me.Think all 27 have more value? pic.twitter.com/koU3O6RTmD

— Ryan Spilborghs (@spillygoat19) September 15, 2015

The stats have changed a little since, but not by a lot. Nolan Arenado is still in the cluster of players in fWAR rankings from 20 to 30. He now has 4.3 fWAR. The best answer to Spilly’s question about Arenado’s seemingly low WAR was that it was a combination of a low on-base percentage, probably overshot park adjustments, and maybe not enough credit to his defense (read Matt Gross's full explanation here). The tweet got me thinking: How typical are batter seasons where a player has a similar combination of OBP, run creation, and WAR? It’s not typical at all. In fact, such seasons are rare.

To find the answer, I used Baseball Reference’s Play Index. Because of that, I used their measures of run creation, OPS+ instead of FanGraphs’ wRC+, and WAR. These different stats approximate one another, and OBP remains OBP. Through Friday’s game, Arenado has a .320 OBP, a 121 OPS+, and 5.2 bWAR.

I searched for player seasons since 1961 (since expansion and league-wide integration) where the batter had an OBP .320 or under, an OPS+ 120 or above, and a bWAR rating of at least 5.0. Excluding Arenado, the search yielded just five player seasons.

The first thing to note is that this list includes some pretty good players. That makes sense. Five-win players tend to be quite good. It also makes sense because we already know that Arenado is a pretty good player. Another thing to note is that none of the five players here appear twice on the list. They are rare seasons on a macro scale, and at the individual level they are singular. Most importantly, we have to recognize the context out of which these seasons emerged, particularly league average OBP.

Three of these seasons took place in the 1960s. In 1963, Felipe Alou produced runs at least 20 percent better than average with an OBP under .320. It was just barely under at .319. Not only that, but in 1963 the league average OBP was .309. He was better than average. For his career, Alou posted four 5 bWAR seasons, and in each of the other ones his OBP was above .320. They also all took place in the run suppressing ‘60s.

Johnny Callison had a four year stretch from 1962 to 1965 where he posted a 6-win season, followed by an 8-win season, followed by two more 6-win seasons. In 1964, the year after Alou, the outfielder managed to do so despite a .316 OBP. As opposed to Alou’s above average OPB season, Callison’s was essentially league average. In 1964, it was .313. Callison’s OBP was only league average in a great season due to a low walk rate, 5.1 percent. One can also point to his from today’s standards low BABIP, .278, but that was almost perfectly on target to the league’s .279 BABIP.

Hall of Famer Reggie Jackson had the best career of the five names on the list above. In 1968, Jackson was in his second big league season, and he posted one of his eight seasons with at least 5 bWAR. After that season, Jackson didn’t have one with an OBP under .320 until 1983, when he was 37. Additionally, Jackson’s .316 OBP in 1968 was well above average for that season, which was .299.

The run environment was different for the other two players on the list. The only one of these seasons that was anomalous in terms of WAR for the player was Tony Armas. The outfielder followed his 5.9 WAR season with a 4.2 WAR season, but he never came close to matching either for the remainder of his career. He had a two-year peak. Low on base rates were typical for him. Armas never posted a season with an OBP above .320 and finished his career with a .287 mark. In 1980, his 5-win season, Armas’s .310 OBP was well below league average for the season, which was .326.

In 1991, Matt Williams had a .310 OBP and a 129 wRC+ in one of his two 5-win seasons (he would have made it in 1994 and 1995 if the seasons weren’t shortened). Like Armas, his OBP was below the league average .323. Williams defied the odds with a season altogether to go along with a low on base rate. Williams’s 5.2 percent walk rate and .286 BABIP, which was low-ish, were the reasons for his low OBP.

The five seasons identified based on my search criteria are somewhat misleadingly assembled together because they played in different run environments. Alou and Jackson had above average OBPs, though they weren’t superstar level. Callison’s season, the other that took place in the 1960s, was about league average. Armas’s 1980 and Williams’s 1991 took place in better offensive years. Those high run-creation and high value seasons defied the low OBP.

Arenado might not end up fitting the criteria to join Alou, Jackson, and the others. If he does, however, he’s unlikely to do so more than once, and probably not because his OPS+ will fall below 120. Arenado’s low walk rate coupled with his low-ish .282 BABIP has dampened his run creation and, consequently, his overall WAR, regardless of the particular model.

Nolan Arenado’s 2015 OBP isn’t low—it’s just pretty average given the current run environment. Arenado’s .320 OPB is ahead of the league average .317 OBP; his .355 home OBP is a tick under Coors Fields’ composite OBP, which is .357. The averageness of Arenado’s on-base percentage is inarguable. But what can be contested is the extent to which that matters. Aside from speed, it’s the only area of Arenado’s game where he doesn’t excel. It just happens to be a pretty important area. The hair I’m about to split is also significant: the difference between an average and an above average OBP for Arenado is the difference between stardom and superstardom.