Arizona Diamondbacks vs San Francisco Giants Prediction 5/20/26 MLB Picks Today

The San Francisco Giants and the Arizona Diamondbacks meet Wednesday in MLB action from Chase Field. We will look at this from a betting perspective and determine the best bets for this game. Here’s a San Francisco Giants vs. Arizona Diamondbacks prediction.

Starting Pitching Matchup

The San Francisco Giants will send out Tyler Mahle for the start here and Mahle is 1-5 with a 5.59 ERA and 48 strikeouts this season. In his last five starts against Arizona, Mahle is 0-1 with a 1.80 ERA and 40 strikeouts. Merrill Kelly will start here for Arizona and is 3-3 with a 5.91 ERA and 23 strikeouts this season. In his last five starts against the Giants, Kelly is 2-1 with a 3.41 ERA and 26 strikeouts.

San Francisco Giants Recap

The San Francisco Giants come into this game looking to bounce back from a 5-3 loss at the hands of the Diamondbacks last time out to sit at 20-29 this season. After this series, the Giants will square off against the Chicago White Sox at home.

Giants Drop Back-To-Back Games

Luis Arraez has 57 hits with 9 doubles, 2 triples and 16 RBIs while Willy Adames has 44 hits with 14 doubles, 3 home runs and 13 RBIs along with 56 strikeouts. Matt Chapman has 39 hits with 11 doubles, a triple, a home run and 16 RBIs and Jung Hoo Lee has 47 hits with 10 doubles and 17 RBIs. Heliot Ramos has 44 hits with 12 doubles, 4 home runs and 20 RBIs this season. Rafael Devers also has 44 hits with 10 doubles, 5 home runs and 19 RBIs but also has 59 strikeouts this season.

Arizona Diamondbacks Recap

The Arizona Diamondbacks come into this game looking to add on to their win over San Francisco last time out to sit at 24-23 this season. After this series, the Diamondbacks will take on the Rockies in a series rematch at home.

Diamondbacks Win 3 In A Row

Corbin Carroll has 42 hits including 11 doubles, 4 triples, 7 home runs and 24 RBIs while Alek Thomas has logged 9 doubles with 2 home runs and 10 RBIs as well this season. Ketel Marte has 36 hits with 6 doubles, 5 home runs and 15 RBIs and Geraldo Perdomo has 33 hits, with 7 doubles, 3 triples, 2 home runs and 12 RBIs as well this season. Nolan Arenado also has 39 hits with 7 doubles, 6 home runs and 21 RBIs and Jose Fernandez has 33 hits with 3 home runs and 14 RBIs this season. Ildemaro Vargas also has 51 hits with 8 doubles, 2 triples, 7 home runs and 31 RBIs.

San Francisco Giants @ Arizona Diamondbacks Betting Trends: May 20, 2026

• Probable Starting Pitcher: Merrill Kelly      Record this season: 3-3      ERA: 5.91
• Home Record: 1-1
• Last 5 against Giants: 2-1

Why the Arizona Diamondbacks will win

• The Giants have lost eight of their last nine road games following a loss.
• The Diamondbacks have won each of their last four home games.
• The Diamondbacks have covered the run line in eight of their last nine home games against National League opponents following a win.
• The Giants have failed to cover the run line in each of their last four games against NL West opponents.
• The Diamondbacks have won the first inning in six of their last seven home games against NL West opponents that held a losing record.
• The Diamondbacks have led after 3 innings in eight of their last 10 games as favorites against National League opponents.
• The Diamondbacks have led after 5 innings in seven of their last nine home games against NL West opponents that held a losing record.

• Probable Starting Pitcher: Tyler Mahle      Record this season: 1-5      ERA: 5.59
• Road Record: 0-3
• Last 5 against Diamondbacks: 0-1

Why the San Francisco Giants will win

• The Diamondbacks have lost each of their last seven Wednesday home games against National League opponents.
• The Giants have won four of their last six games as underdogs against NL West opponents following a loss.
• The Giants have covered the run line in eight of their last nine day games against National League opponents following a road loss.
• The Diamondbacks have failed to cover the run line in five of their last six day games against NL West opponents following a home win.
• The Giants have led after 3 innings in each of their last three road day games.
• The Giants have led after 5 innings in each of their last three road day games.

Total Runs Facts

• Seven of the Diamondbacks’ last eight day games as favorites have gone UNDER the total runs line.
• Six of the Giants’ last seven day games against NL West opponents have gone UNDER the total runs line.
• The ‘Inning 1 OVER 0.5 runs’ market has hit in six of the last seven games between the Giants and Diamondbacks.
• The ‘Inning 1 OVER 0.5 runs’ market has hit in six of the Giants’ last seven games at Chase Field.

Arizona Diamondbacks Player Prop Facts

• Lourdes Gurriel Jr. has hit a home run in two of his last three appearances in day games against NL West teams that held a losing record.
• Merrill Kelly has recorded a win in four of his last five appearances at Chase Field against NL West opponents that held a losing record.
• Merrill Kelly has recorded five or more strikeouts in each of his last eight home appearances against NL West opponents that held a losing record.
• Corbin Carroll has recorded at least one hit in each of his last 13 appearances with the Diamondbacks as favorites against the Giants.
• Ildemaro Vargas ranks 2nd amongst qualified players for Batting Average (.340) this season.

San Francisco Giants Player Prop Facts

• Willy Adames has hit a home run in each of the Giants’ last two games.
• Tyler Mahle has recorded five or more strikeouts in each of his last seven appearances against opponents that held a winning record.
• Rafael Devers has recorded at least one hit in each of the Giants’ last seven games against NL West opponents that held a winning record.
• Luis Arraez ranks T2nd in the league in Hits (58) this season.

Matchup/League Facts

• The Diamondbacks rank 1st in the league for triples this season (14).
• The Diamondbacks rank 29th in the league for strikeouts this season (346).
• The Giants rank 30th in the league for runs scored this season (170).
• The Giants rank 30th in the league for RBIs this season (164).

San Francisco Giants vs. Arizona Diamondbacks Prediction

I’m backing the Diamondbacks here. Merrill Kelly has started to right the ship on the mound, and has had some real success against this Giants squad over the last couple of seasons to where I think he can do it again in this one. San Francisco just continues to have offensive issues and Tyler Mahle for me might be the weakest link of San Francisco’s starting rotation. Give me the Diamondbacks here.