Art McGee on valuation: Revising player values during the season

by on June 16, 2009 @ 00:00:00 PDT


Note: This article by Art McGee was originally published on

Rotisserie owners usually think about player valuation in conjunction with their draft, but knowing just how much a player is worth can be important during the season as well, particularly when you are evaluating trade possibilities.

The basic measure of a player's value is the same whether you're preparing for Draft Day or considering a late-season deal. What you need to know is: How many points will this player gain for me in my league's standings? Obviously, you want to make trades when you can acquire more points in the standings than you are giving away.

Once you have your best projection of the player's performance for the rest of the season, you need to convert those stats into Standings Gain Points (SGP), the number of points that those stats will likely be worth in your league standings.

Using the formulas will give you player SGP values for a typical team in a typical league. If these were the correct formulas for all Roto owners to use, then the only time that owners should make trades would be when they disagree about the expected performance of one or more players.

Of course, many trades do take place for just that reason. But trades often take place for another reason... depending on the situations of particular teams in a particular league, the same set of stats may have different SGP values.

Before the season, the formulas are appropriate for just about any team, because an owner can hardly predict before Draft Day whether or not he will be in a tight race in a given category. As the season progresses, however, and the standings start to sort themselves out, the SGP value of a specific stat will change depending on a team's situation.

Then, to determine appropriate player values you must adjust the SGP formulas according to your specific situation. Here are a few common scenarios with the corresponding adjustment to the formula:

Tight categories: If your team is in a tight race in a particular category, then any contribution in that category is more likely to help your team in the standings. To reflect this, you should lower the denominator in the formula for that category. For instance, let's say the NL formula for home runs is:

HR SGP = HR / 9.1

The value 9.1 represents the average difference between teams in the HR category at the end of the season. If teams are bunched together in HR in your league, you may want to lower this value to, say, 6.0. Then, a player expected to hit 18 more HR will be worth three standings points to you, rather than just two.

Spread-out categories: As you might expect, you can reverse the logic above if a category is unusually spread out. If that were the case in HR, you might want to increase the denominator in the formula to 12, which would make you more likely to trade away a power hitter.

First place/last place: If your team is comfortably in first place in a particular category, then you can forget about the formula when considering whether to acquire a certain player. There's nothing that player can do to help you in that category -- his SGP are zero. Likewise, if you're in last, you need not calculate the value you will lose in that category by trading away a certain player. You have no more points to lose.

Rate-of-performance categories: In cumulative categories, like HR, a given performance will help most teams in your league by about the same amount. But in rate-of-performance categories, like BA, ERA, and ratio, player stats that will help one team might hurt another. A player expected to bat .275, for example, might lower the BA of the top teams in that category, but it would raise the BA of the bottom teams.

To adjust the SGP formula for your own analysis, substitute your team's expected BA for the league average BA provided in the formula. Assume your team is on track for a .267 average. Instead of using the standard formula, which is:

BA SGP = (((1498.8 + Hits ) / (5450 + AB)) - 0.275) / 0.002

you should use:

BA SGP = (((1455.2 + Hits ) / (5450 + AB)) - 0.267) / 0.002.

Make sure you adjust the number of hits at the beginning of the formula to be consistent with the BA you plug in near the end. In this case:

0.267 BA x 5450 AB = 1455.2 hits

One thing you should notice right away about these calculations is that a player will help you more in the standings if you acquire him earlier in the season. Adrian Gonzalez will move your team up more places in the HR category if you trade for him now than if you wait until August to acquire him.

So, there's no time like the present to start evaluating trade possibilities.

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