ST. LOUIS --- If you're wondering how Jordan Hicks can add 2 mph to what was already a 103-mph sinker, you're not alone. Hicks' manager and teammates -- along with the rest of the baseball world -- were asking the same question after the 21-year-old twice eclipsed 105 mph with his fastball in Sunday's 5-1 win over the Phillies.

Hicks pointed to the batter's box for the answer.

"Odubel just takes forever to get in the box," Hicks said, referencing Phillies center fielder Odubel Herrera . "It amps me up a little bit. So I bring it against him."

The five pitches Hicks fired to Herrera in a ninth inning at-bat Sunday were the five fastest pitches of the 2018 season thrown by any pitcher, per Statcast™. Two registered at 105 mph. The others: 104.3, 104.2 and 103.7. In doing so, Hicks eclipsed Yankees closer Albertin Chapman as the game's hardest thrower this season. He and Chapman are the only pitchers to hit 105 mph since pitch tracking began in 2008.

The scoreboard readings had Hicks' teammates clamoring in the dugout.

"You see 105 up there. That doesn't happen. I don't know what the exact mph was, but we're all wondering if it was 105 point, or where on 105 it was," said starter Jack Flaherty, who tossed 7 2/3 brilliant innings in the win. "I wish I could throw 105."

Hicks has spent the majority of his rookie season battling other relievers for the title of MLB's hardest-throwing pitcher. He says he keeps surprising himself, as the radar reading continues to climb. Hicks broke camp with a reputation of hitting 102 with his sinker, which runs down and arm-side and, thanks to his age and power arm, can disobey him at times. Saturday he touched 103 mph -- also against Herrera.

"[He] doesn't irritate me. Just like … get in the box. It's all good though," Hicks said. "I saw the 103 last night and said, 'Oh, I guess I can do that. I'll try to throw a little harder today.'"

Hicks has thrown his seven hardest pitches of the season against Herrera.

"It was my first time facing a guy like that," Herrera said. "I had never faced someone throwing 104, 105 miles an hour. But I felt good because I was able to see pitches."

Here are some more fireballer facts:

• Chapman had previously thrown the fastest pitch of 2018 on May 8, when he hit Red Sox outfielder Jackie Bradley Jr. with a 103.3-mph pitch.

• Hicks is now just the fourth pitcher to reach 104 mph in pitch-tracking history, joining Chapman, Mauricio Cabrera (2016) and Neftali Feliz (2010).

• Hicks owns eight of the 10 fastest pitches thrown this year, and 13 of the top 20.