Royals vs. Giants Prediction, Odds, Probable Pitchers and Prop Bets for Wednesday, May 21

Bettors should expect yet another low-scoring game in this series finale.

San Francisco Giants starting pitcher Logan Webb is a great prop target on Wednesday. / Robert Edwards-Imagn Images

The Kansas City Royals and San Francisco Giants play the rubber match of a three-game set on Wednesday afternoon in what should be a fun pitching matchup.

The Giants have ace Logan Webb on the mound, as he looks to build on a strong month of May, where he’s allowed just four earned runs in 22.0 innings of work. The Royals are going with an opener in this matchup, as Daniel Lynch IV (1.29 ERA) is set to get the start.

Kansas City’s bullpen has been one of the best in MLB this season, posting a 3.14 ERA. 

Still, oddsmakers have the Giants set as sizable favorites with Webb on the mound, as they’ve been one of the best home teams in MLB (17-8) through the first two months of the season.

Here’s a breakdown of the odds, my favorite player prop and a game prediction for this series finale. 

Royals vs. Giants Odds, Run Line and Total

Odds via DraftKings Sportsbook.

Run Line

• Royals +1.5 (-120)
• Giants -1.5 (+100)

Moneyline

• Royals: +170
• Giants: -205

Total

• 7.5 (Over +102/Under -122)

Royals vs. Giants Probable Pitchers

• Kansas City: Daniel Lynch IV (3-0, 1.29 ERA)
• San Francisco: Logan Webb (5-2, 2.42 ERA)

Royals vs. Giants How to Watch

• Date: Wednesday, May 21
• Time: 3:45 p.m. EST
• Venue: Oracle Park
• How to Watch (TV): NBCS-BA, FDSKC
• Royals record: 27-23
• Giants record: 29-20

Royals vs. Giants Best MLB Prop Bets

Giants Best MLB Prop Bet

• Logan Webb UNDER 2.5 Earned Runs Allowed (-160)

Earlier today, I shared in SI Betting’s MLB Best Bets column – Walk-Off Wagers – why Logan Webb is worth a look in the prop market: 

This season, Webb has been great for the Giants, posting a 2.42 ERA and 2.08 FIP across 10 starts.

He has a solid matchup on Wednesday afternoon, as the Kansas City Royals are just 26th in MLB in OPS and 27th in runs scored in the 2025 season.

Webb has given up two or fewer earned runs in seven of his 10 starts in the 2025 season, and he’s been lights out this month, posting a 1.64 ERA in three starts. Webb has tossed at least seven innings in each of his May outings. 

I’m buying the Giants ace in this matchup, and his advanced numbers show that he’s been one of the better pitchers in baseball in 2025. Webb ranks in the 84th percentile in expected ERA, 85th percentile in barrel percentage (he’s inducing a lot of weak contact) and 79th percentile in strikeout percentage.

I’ll back him to keep his strong month of May going on Wednesday.  

Royals vs. Giants Prediction and Pick

These are two of the best pitching staffs in the league – especially when looking at the bullpens.

San Francisco is No. 1 in the league in bullpen ERA (2.63) while the Royals are fifth in the 2025 season.

With Webb on the mound for the Giants, I lean with them to win this game, but the -205 price on the moneyline is a little too rich. Instead, I’m looking to the total – specifically the UNDER – in this interleague matchup.

Kansas City’s offense has struggled in the 2025 season, ranking 19th in batting average, 26th in OPS, and 27th in runs scored. That’s led to the Royals being one of the best UNDER teams in MLB, going 33-16-1 to the UNDER in 50 games.

The Giants have hit the OVER (26-22-1) more often this season, but they have finished with seven or fewer combined runs in half of Webb’s outings. The All-Star right-hander has not allowed more than three earned runs in a single start this season.

Plus, the San Francisco offense is far from elite, ranking 17th in OPS, 10th in runs scored, and 22nd in batting average.

Against a tough Kansas City bullpen, I don’t think San Fran scores enough to push this game over the total. The first two games in this series have finished with four and five combined runs. 

Pick: UNDER 7.5 (-122 at DraftKings)

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Odds refresh periodically and are subject to change.

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