⚾ Who Will Win MLB Rookie of the Year? Win Probability for Griffin, McGonigle After Week 1

The MLB Rookie of the Year market experienced a massive swing on Thursday as the Pittsburgh Pirates called up baseball's No. 1 prospect, Konnor Griffin, to join the big-league club. As a result, the best prediction market apps have made Griffin the favorite to win NL Rookie of the Year. But what does the rest of the market look like?

We've dug into the MLB Rookie of the Year win probability after one week of the 2026 season and look to uncover who will be crowned baseball's top rookie this year. Both the AL and NL feature significant standouts, but there's also a ton of value lower down the board, and that's what we're targeting with our best picks.

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📊MLB Rookie of the Year win probability: Who will win AL ROY in 2026?

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Unlike the Pirates, the Detroit Tigers had Kevin McGonigle start the campaign in the majors, and he hasn't disappointed. He's batting .364 over his first six games and is a significant favorite to win AL Rookie of the Year after one week, with a 31% probability at Kalshi.

Just behind McGonigle is Chase DeLauter, who's crushed four homers in six games for the Cleveland Guardians. He sits at 25%, while Munetaka Murakami is at 20% after his own homer-powered hot start for the Chicago White Sox.

Kalshi has no other player outside of those three with a win probability greater than 10% after one week of the season.

AL Rookie of the Year win probability after 1 week

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🏆 Who will win AL Rookie of the Year? Latest win probabilities

Let's take a look at the favorite in this market at Kalshi, and compare his win probability and the potential profit you'll make on a successful Yes selection with an investment of $10.

Favorite: Kevin McGonigle (31%)

If you buy $10 worth of Yes shares on McGonigle at this current price, you'll profit $23 if he's crowned AL Rookie of the Year. I don't think that's a particularly bad price on a player like McGonigle.

He's thus far shown an ability to get on base - with a .440 OBP - and play solid defense. However, he doesn't hit the ball particularly hard, and he's yet to hit a home run or steal a base. I think he's going to need to rack up at least one of those to truly compete for this award.

Accruing the most WAR is great, but a player is going to have a hard time winning Rookie of the Year if they finish with something hovering around 15 home runs and 10 stolen bases, especially if the competition is putting together eye-popping counting stats. And there's one player in particular who I think can do just that, and his win probability at Kalshi is much lower than I think it should be.

My pick: Kazuma Okamoto (9%)

Okamoto was my preseason pick to win AL Rookie of the Year, and he's gotten off to a strong start. He's already swatted a pair of homers, and he's been massively important to a Blue Jays team featuring many players suffering from some regression from the 2025 campaign.

This 9% win probability represents a massive bargain in the market, as a $10 investment on Yes would result in a $102 profit if Okamoto wins AL ROY. For some context, that's equivalent to odds of around +1000, and I think a more fair price on Okamoto is closer to +500 to +600.

Outside of a slightly alarming strikeout rate, Okamoto looks like the real deal, and he's even playing solid defense. I think he can pretty easily hit 30 homers and act as a centerpiece of one of baseball's World Series contenders. If he does that, you'll look back at this in September and realize you got an absolute steal.

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📊MLB Rookie of the Year win probability: Who will win NL ROY in 2026?

This morning at 7:44 a.m. ET, Griffin's Yes price at Kalshi was 18 cents (or an 18% probability). Eight hours later, following the announcement that he's getting the call to the majors, that sits at 29%, and he's now the overwhelming favorite.

Interestingly enough, this is actually almost right in line with how Kalshi listed him throughout spring training, and I was telling people then to wait for an announcement. As we can see, the announcement didn't make this price go beyond that one. It's not as if he's suddenly trading at a 40% probability. The best course of action was to wait until the season began and pounce on a good number.

If you bought Yes on Griffin when he was hovering around 17 to 19 cents, you're laughing now. That's the difference between a profit of around $50 on a $10 investment vs. the return of $25 you'd get now. So, with that in mind, should you still buy Yes on Griffin, or is there a better option?

NL Rookie of the Year win probability after 1 week

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🏆 Who will win NL Rookie of the Year? Latest win probabilities

Listen, I don't think there's anything wrong with still investing in Griffin. As you'll see below, my faith in him is very much apparent. However, I do think another player offers better value based on how this pricing currently stands.

Favorite: Konnor Griffin

Griffin has, without a doubt, the highest ceiling of any rookie in MLB this year - AL or NL. He could steal upward of 40 bases and pop around 20 homers. His speed and defense should keep him in the Pirates' lineup every day, and it's entirely possible he plays his way into a premium spot in the order if he isn't just given one straight away.

However, his win probability is obviously also sky-high. You would make only $25 in profit on a $10 investment on Yes right now, and that's not exactly ideal. So, I'm going to present another option; a player who has a ceiling nearly just as high at Griffin's but is providing you with much better value on your dollar.

My pick: Nolan McLean

When Griffin started the campaign in the minors, I immediately backed Nolan McLean as my preseason pick.

His season-long projections are great, and he was being treated in fantasy leagues as a borderline SP2. In fact, he was drafted in my quite competitive 12-team season-long Roto league ahead of some majorly hyped pitchers like Jacob Misiorowski, Chase Burns, Cam Schlittler, and Emmet Sheehan, as well as veteran studs like Nick Pivetta, Tyler Glasnow, and Nathan Eovaldi.

McLean looked sharp in his first start, too, striking out eight over five innings, managing an absurd 36.9% called + swinging strike rate for the game. We saw how good this dude looked in the WBC final against a loaded Venezuela team, and to me, he's still the best pick when it comes to NL Rookie of the Year. The fact that you'll profit $53 on a $10 investment is just the icing on the cake.

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⚖️ How to trade on MLB Rookie of the Year

What is Kalshi and how does it work?

Kalshi is a U.S.-regulated prediction market exchange overseen by the Commodity Futures Trading Commission (CFTC), where users trade on real-world outcomes using simple Yes/No contracts.

Each contract pays out $1 if the outcome happens and $0 if it does not. If you think Konnor Griffin will win NL Rookie of the Year and buy a "Yes" contract at 29 cents, that implies a 29% chance. If Griffin wins, the contract settles at $1, netting you 71 cents per share. If he loses, it settles at $0. Prices fluctuate in real time as users buy and sell, so the market reflects the crowd's collective expectations and shifts with every game played, injury update, and any additional roster news.

How to read prediction market odds

Kalshi displays prices in cents, which represent the implied probability of an outcome. Griffin at 29 cents means the market prices a 29% chance he wins NL Rookie of the Year - buy "Yes" at 29 cents and collect $1 if they win, profiting 71 cents along the way.

Here's a simple breakdown of the conversion from Kalshi prices to American odds:

How does Kalshi differ from sports betting?

If you've ever placed a bet at a sportsbook, Kalshi will feel familiar but work differently in a few important ways. At a traditional sportsbook, you bet against the house at a fixed line. The book sets the odds, builds in a margin (the "vig"), and you either win or lose at those terms.

On Kalshi, there is no house. You trade directly with other users in an open market. Prices are expressed in cents as implied probabilities rather than traditional American odds. A contract priced at 20 cents implies a 20% chance of winning - the same information as American odds, just presented differently. There is no vig baked into a fixed line; instead, the spread between the buy and sell price is how the market operates.

The other major difference is flexibility. A sportsbook bet is locked in once placed. On Kalshi, you can sell your contract at any time before the tournament ends - locking in a profit if the price has moved in your favor, or cutting your loss if your team gets upset.