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MLS Fantasy: Expected Goals for Expected Points

Using Some Advanced Stats to Make Your Picks

Aaron Doster-USA TODAY Sports

Week 7 was another speed bump for managers as unexpected injuries to Plata, Kaka, and Tierney are forcing managers this week to make unexpected transfers. The good news for managers is that with Portland, Sporting KC and Vancouver each with DGWs in both Weeks 8 and 10, there's plenty of opportunities to pick up players that can bring back any points lost last week.  However, if you're picking up players and expecting to hold onto them for 5 matches or more, then you need to be sure that they'll continue to produce the same fantasy value they've produced already.

This isn't an exact science, and depends on a number of variables: home v. away, quality of opponent, injuries, and run of luck. It's that last one that causes managers a lot of trouble, but one that can be neutralized by looking at the underlying numbers of a player. I like to use expected goals as my "underlying number," and the site I've been using this year to find that is American Soccer Analysis. If you're interested in a deep explanation of expected goals, I'd encourage you to read this from SBNation's own Michael Caley.

For a fantasy manager, Expected Goals is a great tool beyond the numbers in the fantasy game that can tell you when a player is going through an unsustainable run of luck, either good or bad.

Looking at Fanendo Adi for example, he's scored 6 goals off of 19 shots (all numbers per American Soccer Analysis, linked above) but he has an expected goals of 5.36. So while the high goal tally off of low shots might seem unsustainable, the numbers suggest that the shots Adi has been taking are high quality chances that he's finishing at a sustainable rate. The creation of those high quality chances has a lot to do with Diego Valeri, who has an Expected First Assist number of 3.38. Looking at this double game week then, I'd be concerned that Adi will struggle in the match at New England but with Valeri returning for the second match against Toronto, he's a solid option.

David Villa also has a roughly equivalent goals to expected goals ratio of 4 to 3.98 (although the numbers don't include the Philadelphia match) but has done so with 30 shots compared to Adi's 19. Now, 30 shots isn't that unusual. Giovinco has 31 shots for a 3.23 xG. But it does suggest that if Villa suddenly loses that number of shots, his goal numbers would go down because he's relying more on volume of chances than a small quantity of high quality opportunities. We've seen first hand NYCFC's brilliant tactical strategy of "pass to Villa and hope Villa does Villa things." If that changes without a corresponding increase in the quality of those chances, Villa's fantasy value would go down.

There are a few players whose goal tallies aren't matching their xG numbers. Piatti had a number of incredible goals, and that's reflected in the numbers: 4 goals with only a 1.8 xG. Piatti still has value in the bonus points he generates, but if you're buying him expecting the goal production he put forth in the first few weeks, you'll be mislead. On the other hand, prior to this week Bradley Wright-Phillips had no goals despite having one of the highest xG numbers of 4.74. In fact, the underlying numbers suggest that Red Bulls aren't bad offensively, they were just going through bad luck. Managers who stuck with the Red Bulls players despite the bad fantasy output were rewarded this past week: Kljestan and BWP scored 15, with Grella scoring 14.

The lesson is this: if a player is on an amazing run, don't waste your transfer until you've made sure that the gravy train has enough steam to keep on rolling. This doesn't replace thinking about opponents, injuries, rotations, or the schedule, but it can help you gain a huge advantage over the average fantasy player that simply transfers in whomever scored a lot of points the last few week.

Lineups lock early this week to accommodate the midweek games (7pm EST), so make sure to get your transfers in and good luck!