SF Giants catcher Patrick Bailey near the top of offensive leaderboard

SAN FRANCISCO — With one crack of the bat, Patrick Bailey made a metaphorical announcement: it’s time to forget about the second half of last season.

Bailey’s three-run, walk-off homer in the ninth inning on Friday night lifted the Giants over the Pittsburgh Pirates, 3-0, the culmination of a player who has quickly evolved into one of the most potent offensive forces in the game.

The numbers are jumping off the page. Throughout the season’s first month, Bailey leads the majors or is near the top of the majors in almost every batted ball category.

“It’s exciting,” he said before Saturday’s game. “I obviously want to start this way instead of the opposite. I’ve had plenty of years where I’ve struggled to hit .150 at this point. So I’m excited with where the adjustments have gotten me but I understand baseball is a tough game. It beats you up.”

The wounds from last year are still fresh.

He had a strong debut in his first 40 big league games, but as soon as the All-Star break ended, Bailey stopped hitting. In the second half, the rookie backstop posted a .514 OPS that ranked dead last out of 175 big leaguers with at least 200 plate appearances. He hit just .188 with two home runs while striking out 60 times in 203 PAs

“He got a little run down at the end, and the at-bats weren’t as good,” Giants manager Bob Melvin said.

After Bailey used the offseason to rebuild his swing, the results are paying early dividends.

“The swing is in a much better spot,” he said Saturday. “I’m using the ground more. I’ve had my highest exit velocities ever. I think the big thing for the higher walk rate is the lack of three-ball chase. And the decrease in the strikeouts come from the swing change, putting balls in play that I should, and not fouling them off or swinging and missing.”

Through the first month of the Giants’ season, Bailey has nearly doubled his walk rate from 6% to 11%, reduced his strikeout rate from 28% to 24%, and pummels the ball whenever he makes contact.

His sweet spot percentage, which ranks players based on a launch angle that most resembles a line drive, is nearly 60%, the best in MLB, while his average exit velocity of 94 mph ranks in the 96th percentile.

Now, baseball’s weakest hitter has become one of the most productive.

“When your swing is in a good spot, you have time to make decisions,” he said. “Whenever you feel like you have to start earlier to get to the heater, your swing decisions are worse because you’re starting the decision process earlier. Now I feel like I can start later, be on time and, in essence, I have more time to make the right decisions whether I’m chasing or not.”

His walk-off homer on Friday was his third long ball in 75 PAs this season. He hit all of seven homers in 353 PAs a year ago.

“If you’re a good hitter, it’s going to show up at some point in time,” Melvin said. “You saw flashes of it last year.”