Friday MLB NRFI Model Predictions & Pick (Sep. 8)

Friday MLB NRFI Model Predictions & Pick (Sep. 8) article feature image

Mike Stobe/Getty Images. Pictured: Luis Severino

Yet again this week, we turned a slight profit on Thursday, winning the full-unit play but losing the half-unit dart throw.

Let's have a big day today as we head into the first full football weekend of the fall.

The MLB NRFI Model

The process is relatively simple. First, I start by assuming that the full game (implied) run totals for either team are roughly efficient. As mentioned above, that tends to be the case more often than not. This saves me the trouble of trying to predict the total runs scored in the game — and allows me to focus strictly on the "when" rather than "how many."

Next, I built a database of pitchers performance the first time through the order, relative to their overall stats. Since the latter is presumably baked into the full game total, I wanted to figure out if those runs are more likely to come early or late. Most — but not all — MLB starters do somewhat better early in games, but with some variance in just how much. The model uses xFIP (expected Fielding Independent Pitching) as the ERA predictor of choice.

That's only half of the equation, though, with the offenses making up the other half. To do this, I looked at what percentage of a team's total runs is produced by the top three batters in the lineup. While a first inning run scored, by definition, needs at least four hitters to come to the plate, one of the first three has to actually score it. The metric of choice here is wRC+, based on the projected lineup for the day from each team.

This is a bit of a tradeoff, as lineups (and run totals) can shift throughout the day, especially if significant contributors miss time. However, in my experience the inefficiency of the morning lines more than makes up for the leakage in the model. With that said, exercise caution if, say, Mike Trout is listed as questionable for the nights game.


With all of the picks below, I'll include the pick, the best line and the threshold I'd bet it to. These will go up in the morning, so if any major news breaks between publishing and when you read it, be sure to consider that.

Infrequently, rather than betting on the traditional YRFI/NRFI, the pick will be on one team or the other specifically to score a run, which as of this writing is only a betting option at DraftKings. Since the model handles each team individually, sometimes one team is projecting for a greater proportion of the "run equity" in the first inning than the betting lines are accounting for.

NRFI Odds, Picks for Friday, Sep. 8

Arizona Diamondbacks vs. Chicago Cubs (NRFI): The 7.5-run total is the biggest factor, as it points to the likeliest outcome in this matchup. Zac Gallen has been dominant the first time through the order with a 2.20 ERA, and while the Cubs' Jameson Taillon has been worse, I'm generally OK with taking on one-sided risk.

Chicago White Sox vs. Detroit Tigers (NRFI): The Tigers' offense has been annoyingly productive lately, but the math still points heavily to the under here. Mike Clevinger does his best work early in games, and these are two bottom-five offenses against right-handed pitching on the season.

Tampa Bay Rays vs. Seattle Mariners (YRFI): Even with solid starting pitching, getting this one at even money is a steal. Both offenses are fairly top-heavy, and both rank inside the top 10 overall against righties. While neither pitcher is one I'd go out of my way to pick on, they're not especially dominant in the first inning, either.

Milwaukee Brewers vs. New York Yankees (YRFI): How you feel about this one depends largely on your feelings about Luis Severino, who's been awful on the season but turned in a few solid starts lately. Still, he has a 7.24 ERA his first time through the order, and Brewers starter Colin Rea is at 3.43. With both offenses getting a heavy share of their production at the top, one or both should be able to score early here.

Oakland Athletics vs. Texas Rangers (Rangers-only YRFI): Texas is implied for five runs today, and Oakland starter Paul Blackburn has a worse xFIP his first time through the order (4.63) than overall (4.03). With the Rangers as one of baseball's top offenses against righties and one of the more top-heavy, they're far more likely to score than their +195 odds.

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