The Possibilities and Limitations of wRC+ for Fantasy Managers
Here are two players who accumulated over 450 PAs in 2022 and a few stats to accompany them, choose one for your fantasy team:
Player A, DH
128 wRC+
18 HR
0 SB
FanGraphs Auction Calculator YTD 2022 Value (Default settings): $1.5
Player B, DH
119 wRC+
16 HR
0 SB
FanGraphs Auction Calculator YTD 2022 Value (Default settings): $9.6
Surely, you wouldn’t just choose player A without wanting to know more but if you had to choose, you absolutely had to, you would choose player A, right? You would do this because Player A’s wRC+ is higher and he hit more home runs. But now look at the rest of the roto stats each player accumulated in 2022:
Player A, DH
128 wRC+
18 HR
0 SB
.238 AVG
47 R
59 RBI
FanGraphs Auction Calculator YTD 2022 Value (Default settings): $1.5
Player B, DH
119 wRC+
16 HR
0 SB
.274 AVG
76 R
62 RBI
FanGraphs Auction Calculator YTD 2022 Value (Default settings): $9.6
With this new information, you would have to choose Player B. You would surrender two home runs for 29 more runs and three more RBI. But, is it fair to say those runs and RBI minus two home runs are worth $8? And why is Player A’s wRC+ 9 points better? Let’s start digging and then we’ll see if we can find our way back out.
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wRC+ is by our definition, “the most comprehensive rate statistic used to measure hitting performance”, but it places heavy emphasis on runs. Here are the correlations between wRC+ and fantasy stats from the 2022 season (over 200 PAs):
| wRC+ | |
|---|---|
| wOBA | 0.99 |
| OBP | 0.87 |
| Dollars | 0.75 |
| AVG | 0.72 |
| HR | 0.69 |
| RBI | 0.67 |
| R | 0.66 |
| PA | 0.50 |
| SB | 0.13 |
Player A wOBA: .349
Player B wOBA: .343
Intuitively that makes sense. The statistic is called weighted runs created plus. But, it can be confusing if we consider our two examples above. Player A literally scored less runs himself and drove in less runs than Player B, yet he has a larger wRC+.
Let’s do some nitty-gritty mathematics and calculate each players wRC+ manually to see if we can surmise what’s going on:
wRC+ = (((wRAA/PA + League R/PA) + (League R/PA – Park Factor* League R/PA))/ (AL or NL wRC/PA excluding pitchers))*100
Player A wRC+ = (((14.4/461 + .114) + (.114 – .975 * .114))/ (10,600/91,118))*100 = ~128
*Played in the NL
Player B wRC+ = (((15.7/596+ .114) + (.114 – 1.06 * .114))/ (10,227/90,850))*100 = ~119
*Played in the AL
Even if we changed this calculation and placed player A in Player B’s league, creating the same denominator for both players, Player A would actually increase in wRC+. No, the issue is not league-specific or even park-specific, it is in the plate appearances. Player A was simply more productive in wRAA because he didn’t get enough plate appearances to maybe go through a few additional slumps. So, Player A has a better wRC+ because he was more productive with the plate appearances he was given, even though Player B was able to accumulate more statistics. That’s really the essence of what’s going on here. Player B accumulated more raw stats for your fantasy team than did Player A.
But, does it mean that if a player finished the season with an above average (over 100) wRC+ they have returned positive value? Well, it depends on how much you’ve paid as the fantasy manager, but in general, no.
There can be plenty of situations, most plate appearance based, where a player may post above average wRC+, but does not bring positive value or is no better than a replacement-level player. Take, for example, Lars Nootbaar who posted a 125 wRC+ in 347 plate appearances with an 8.9 wRAA. That’s above average. But over the course of an entire season, there were plenty of other outfielders who would have been better for your fantasy team. If you had an injury and were able to replace that injured player with Nootbaar for those 347 plate appearances, swell! But, when compared to the player pool given by the auction calculator, Nootbaar’s 2022 season cost fantasy managers $0.50. On the flip-side of this argument is Jose Trevino. Though significantly hurt by his poor production (-4.7 wRAA/91 wRC+) he still generated $4 in value because of the large positional adjustment he receives for being a catcher. This just goes to show how important using the right statistic is when it applies to your fantasy team. Had you looked at Trevino’s wRC+ and thought, “Oh, he’s below average”, you would have missed out on a $4 catcher.
The main rule of thumb for when you find yourself down in a hole and looking to get out is to stop digging. Have we found something in the shovels full of dirt? Fantasy managers should not blindly use wRC+ as a metric for selecting fantasy value. Plate appearance accumulation is still king. But, if you’re the type to zig while everyone else zags, you may be able to use wRC+ to find fringe-level players who others have looked over. If you look at the 0 line in the scatter plot above, just above it are players who were worth $1. In addition, there are a number of players who returned negative value but were very productive at the season’s end. While wRC+ has become more and more common as a one stop shop type of offensive production metric, perhaps it is falsely molding your competitor’s impression of a player and therefore can be used to your advantage.
Player A: Daniel Vogelbach (park factor was the average of Pirates and Mets)
Player B: J.D. Martinez