KISSIMMEE, Fla. (AP) For Tyler Flowers and his fellow catchers, the slightest flex of the hand, the smallest twitch of the arm, can make the difference between a ball and a strike.
That, in the end, can decide whether a team wins or loses.
''If you can get that borderline pitch with runners on first and second and nobody out,'' said Flowers, a catcher for the Atlanta Braves, ''it changes the whole dynamic of the at-bat, which in turn changes the whole dynamic of the inning, which in turn changes the whole momentum of the game.''
Flowers is one of the best in the business at this subtlest of skills, though it's something the average baseball fan is unlikely to notice. It's called ''framing the pitch'' - that is, catch it in such a way that it looks more like a strike than a ball.
And, no, we're not talking about those obvious-looking attempts to deceive the umpire on pitches far outside the strike zone, when a catcher awkwardly snatches his mitt back behind the plate for the whole world to see.
To listen to Flowers after a spring training workout, one quickly realizes it's much more complex than that, so much so that at least two stat services have come up with rankings that attempt to show which catchers are best at transforming marginal pitches into strikes.
''Really, the essence of it is making sure that you get strikes called strikes,'' Flowers said. ''It's not really about stealing pitches. It's more about beating pitches to spots so you can be in a position of strength, to essentially catch the ball right where it hits your glove.''
That's no easy task, requiring a dizzying combination of strength, balance, anticipation and timing.
''If you stick your arm straight out to the right and someone throws a ball into it, it's going to move,'' Flowers explained. ''It's going to move away from the (strike) zone. If you can get to that spot before the ball hits your glove and kind of make an effort back toward the zone, or against ... the flight of the ball, then you're going to be able to counteract that force and essentially catch it where it hits your glove, which is in the strike zone.''
The New York Yankees worked on pitch framing every day at spring training.
''It has been in the game for a long time,'' said former big league catcher Tony Pena, who now coaches for the Yankees. ''Right now everybody puts a lot of emphasis on it because one pitch can make a difference in the ballgame.''
From a pitcher's standpoint, it's not so much about persuading the umpire to call strikes instead of balls (though he's certainly not going to complain if that's the outcome). Instead, said Yankees right-hander Masahiro Tanaka, it's about making the guy on the mound feel better about what he's doing.
When a catcher looks in firmly in control behind the plate, his arms and body barely moving, it rubs off on the pitcher.
''It gives you sort of a feeling that you're pitching well that day,'' Tanaka said through a translator. ''In that sense, maybe, it builds a little confidence in yourself.''
That also affects the way an umpire views a pitch. The best pitch framers are the ones, according to Flowers, who can ''control their body in a fashion that isn't distracting to an umpire, where everything stays smooth.''
''All of a sudden, if you make a big shoulder movement or your body's turning, the perception standing behind the person doing that is, `Oh, this guy's having to make a real effort to catch this ball. It can't be a strike,''' he said.
Low pitches are particularly challenging when it comes to pitch framing. Flowers sounded like he was teaching a physics class as he discussed the intricacies of catching a slider that's breaking toward the ground.
''If you just put your arm out there and let the ball hit your glove, it's going to take your glove even further down,'' he said ''So you're trying to get below that ball so you catch it as you're making an effort to come back up toward the zone. If your timing's right, you essentially just catch it right where it is. You have the exact force, put the exact amount of effort into it, so that both of those things meet equally and it stops right there in place.''
Don't underestimate the importance of a single pitch - perhaps at a seemingly innocuous point in the game.
Flowers remembered a contest last season, when he caught for the Chicago White Sox.
Facing their cross-town rivals, the Cubs, the game was scoreless in the sixth when the Cubs' leadoff hitter walked. White Sox pitcher Carlos Rodon fell behind 3-1 to the next hitter, Dexter Fowler. On a low pitch that Flowers was able to frame well, Fowler took a called strike. He struck out on the next pitch, which allowed Rodon to work around another walk later in the inning.
The White Sox went on to a 1-0 victory.
''You don't know which pitch it will be in the midst of a game,'' Flowers said. ''That 3-1 pitch changed the whole inning.''
Now that there's technology showing how many calls the umpires get wrong behind the plate, the art of pitch framing has taken on even more importance.
Simply put, umpires have improved the accuracy of their pitch-calling since cameras were installed in every stadium, producing real-time data that is used to evaluate the men in blue. With fewer pitches in dispute, the close calls are more crucial than ever.
Flowers knows it's a sensitive subject for umpires, whose very jobs could be at risk if they err too many times.
''I don't know if you should even call it framing,'' he said. ''A lot of umpires don't seem to like that term.''
Catchers have their own ways to judge their performance, with two major statistical services - StatCorner and Baseball Prospectus - providing complex ratings systems. According to StatCorner, Francisco Cervelli of the Pittsburgh Pirates was the best in the game at framing last season, resulting in an extra 1.79 strikes per game, just ahead of Flowers and Yasmani Grandal of the Los Angeles Dodgers.
Look for this stat to become more widespread and refined in the seasons to come.
There's simply too much riding on each pitch.
''Any and every borderline pitch can change the game,'' Flowers said.
Follow Paul Newberry on Twitter at www.twitter.com/pnewberry1963 . His work can be found at http://bigstory.ap.org/content/paul-newberry .
AP freelance writer Mark Didtler in Tampa, Florida, contributed to this report.