Mercer had to reach down and contort his body for the underhanded toss, and he had his back to first base when he barehanded the ball for the force at second. Then he blindly turned and made a strong throw to first to complete a double play.
In the TV booth, Steve Blass exclaimed, "That didn't just happen!"
Not only did it happen, but it was happening for the second time in less than a year.
Last July 28 at San Francisco's AT&T Park, the two teamed up on a virtually identical twin-killing against the Giants. The one difference: That time, Mercer made the stop and backhanded flip to Walker, who was the pirouetting middleman in a double play that protected what became a 5-0 shutout for Vance Worley.
"Great minds think alike," Walker grinned when reminded of that precedent.
"Yeah, I don't think I had to leave my feet for the ball [struck by Michael Morse]," Mercer recalled. "But otherwise, very much alike."
Manager Clint Hurdle was impressed both times, but not surprised, implying that his double-play combination actually practices such maneuvers.
"It's fun to watch them do their work every day, then take five minutes of free play to work on some things that might just turn up in a game," Hurdle said. "A couple of times, it has happened. They're not caught off guard.
"That's a tandem probably under the radar if you break down all the combos in the leagues," Hurdle added.
Interestingly, Walker in the past has called their style of play "vanilla." That is, effective and satisfying, but nothing flashy.
But we've also seen their alter egos, "Vanilla Twice."
Around the horn • Expect the Pirates to take their chances on the basepaths this weekend, even against Cardinals catcher Yadier Molina. Hurdle pointed out that Molina has allowed seven steals and only caught four runners this year.
"I think he's playing through some things," Hurdle said. "We do believe we have a better window of opportunity than we've had in the past."
• Triple-A Indianapolis announced Friday that Pirates pitching prospect Nick Kingham, who left his start Wednesday because of discomfort in his right elbow, has been placed on the Minor League disabled list.
• Left-hander Clayton Richard, signed to a Minor League deal over the offseason, made his season debut for Class A Advanced Bradenton on Thursday night.
Richard, a veteran who could serve as a depth option for the Pirates' rotation, allowed one unearned run on four hits and a walk while striking out five over six innings.
• Pirates center fielder Andrew McCutchen hosted 9-year-old Sean Campbell on Friday as part of ESPN and Make-A-Wish Foundation's "My Wish" series. Campbell wanted to meet McCutchen and play video games with him, which they did on the jumbotron at PNC Park on Friday afternoon. The full event can be seen on ESPN the week of July 19.