On May 5, in the third inning of a scoreless game against the Indians, Royals catcher Salvador Perez unleashed one of the best throws of the 2017 season.
With Indians catcher Roberto Perez running, Royals right-hander Jason Hammel pitched out. Perez received the pitch already out of his crouch, pivoted and threw a strike to shortstop Alcides Escobar, who applied the tag on the runner when he slid over the base. After a review, the runner was ruled out. Perez's throw took just 1.81 seconds to reach second from the time it hit his glove, as tracked by Statcast™, making it the quickest to nab a would-be-base-stealer last season.
Perez, a four-time Gold Glove Award winner, has made a career of cutting down runners on the bases, a skill amplified in the modern game, as the number of attempted steals has halted to record low rates. The relative dearth of stolen-base attempts adds importance to each one, making top-notch throwers arguably more valuable than ever.
But we already knew Perez possessed this elite skill, with his combination of footwork, technique and arm strength placing him among baseball's best behind the dish. Now with Statcast™, we can pinpoint, with some certainty, who else truly belongs in his class.
With a bit of research, we can answer some burning catcher questions.

Which MLB catcher has the strongest arm?
The hardest throw from behind the plate that resulted in a caught stealing came from Yankees backstop Gary Sanchez, who threw out Kansas City's Jorge Bonifacio at second on Sept. 25 with an 88.6 mph throw. Sanchez showed off his arm on the play, hesitating at first and then double-clutching, but still getting enough on the throw to record the out.
• Celebrating Statcast™ star Sanchez
The hardest throw overall from behind the plate came from Angels catcher Martin Maldonado, who uncorked an 89.1 mph laser on July 25 against the Indians. This throw proves, though, that arm strength isn't everything, and that accuracy plays a big role in cutting down baserunners as well. Though Maldonado's throw was plenty hard, it sailed into the baseline, allowing Cleveland's Bradley Zimmer to slide into second safely.

Maldonado averaged 86.5 mph on his "max-effort" throws in 2017, which Statcast™ defines as the average of his throws that reached his 90th percentile and above. That was good for third in MLB behind the Cubs' Willson Contreras' 87.2 mph and Sanchez's 86.6 mph.
Which MLB catcher gets the ball to second quickest?
Just having a strong arm isn't everything when it comes to throwing out potential base stealers. Technique, transfer time and footwork all also play important roles in "pop time," the time elapsed from the catcher receiving the pitch to the infielder receiving the throw. And Statcast™ measures it better than any stopwatch could.
We've already told you Perez sported the best "pop time" on a caught stealing at second base of 2017 at 1.81 seconds. Coming in close for second were Sanchez, Marlins backstop J.T. Realmuto and Pirates backup catcher Chris Stewart, all of whom tossed one-time throws of 1.82 seconds. For reference, 2.00 seconds is considered Major League average.

Perez, Realmuto and Stewart also tied for best average pop time on caught stealings at second base at 1.90 seconds. Sanchez and Contreras were behind them with 1.91-second averages. New White Sox backstop Welington Castillo, who was with the Orioles in 2017, averaged 1.92 seconds. Those differences might not seem like a lot, but in the high-stakes game of stealing bases, every fraction of a second counts.
Which MLB catcher threw out the most runners?
This one is more straightforward, and dependent somewhat on opportunity, at least initially. The Reds' Tucker Barnhart led the way this year on his way to his first career Gold Glove, with 32 runners caught on the bases, edging out Maldonado (29) and San Diego's Austin Hedges (26). Barnhart's 32 caught stealings were the fewest to lead the Majors since Hal Smith and Del Crandall caught 32 each in 1959, which makes sense given the lack of attempts in MLB.

If you look at caught-stealing percentage, however, Castillo's season ranks among the best in a while. He threw out 49 percent of potential base stealers, the highest mark since Kenji Johjima threw out 53.7 percent for the Mariners in 2009. Barnhart ranked second in '17, throwing out 32 of 73 runners (43.8 percent).
The 73 runners that tried against Barnhart were the eighth most in the Majors, behind Contreras (84 attempts), James McCann (78), Stephen Vogt (77), Matt Wieters (76), Jonathan Lucroy (75) and Maldonado (75). Castillo had far fewer chances (just 49).

Which MLB catchers are on the rise?
Statcast™ also allows us to see which young players flashed defensive potential, despite limited playing time. For example, Phillies rookie Jorge Alfaro had just eight max-effort throws tracked by Statcast™, so he didn't qualify in our rankings (we used 100 throws tracked to qualify). But those throws averaged 88.1 mph, giving him one of the strongest young arms.
Given his first chance to play at the big league level at age 26, Pirates rookie Elias Diaz flashed some serious tools behind the dish as well. Diaz unleashed a 91.1 mph throw on Sept. 23 against the Cardinals, though it came after fielding a squibber in front of the plate, not an attempted steal.