ST. PETERSBURG -- Conventional wisdom might suggest that hitters should always take a 3-0 pitch. No exceptions. No matter what.
There's logic behind that line of thinking. If a pitcher has thrown three straight balls to a hitter, he will likely have a difficult time throwing three strikes before he tosses a pitch outside the zone. Even if he does throw a strike, the hitter still has the advantage. They are called hitter's counts for a reason, after all.
As of Wednesday, 2,833 of the 4,455 plate appearances that started with three straight balls ended in free passes. Major League hitters own a .740 on-base percentage in plate appearances that start 3-0, and most of that is a product of the number of walks drawn in those at-bats.
So, why wouldn't a hitter take a 3-0 pitch? What would prompt a manager to give a hitter the "green light" in that count if he has such a strong chance of reaching base anyway?
"It has to be a pitch in your hitting zone," said Rays hitting coach Derek Shelton. "The only pitch in your hitting zone."
The Rays only put six balls in play on 3-0 counts in 2011, four of them hits -- a single, a double and two home runs. Evan Longoria, Tampa Bay's best hitter, was responsible for most of that, going 3-for-3 with the two homers. Infielder Sean Rodriguez had the double.
"It should be a pitch that, if you're going to hit it, you can drive it out of the ballpark," Shelton added.
Plenty of managers will give a hitter the green light in certain situations, but Kirk Gibson has let the D-backs swing away on 3-and-0 more than any club in the Majors the past two seasons.
Arizona has already put the ball in play on 3-0 counts a Major League-high 15 times this season, going 8-for-15 with four homers and a double. Outfielder Justin Upton went 5-for-8 with three homers and a double when he swung away on 3-0 counts last season, and he's 2-for-2 with a homer in those situations this season.
The Yankees and Marlins have reached on every plate appearance that ended with a 3-0 count, meaning the next pitch resulted in a walk, hit batter, sacrifice play or a ball in play. The Marlins are the only club yet to put a ball in play on a 3-0 count this season, while the Yankees have gone 2-for-2 with 64 walks in 66 plate appearances that ended with a 3-0 count.
"It's not that easy," Upton said on June 20, when he took three straight balls then smashed a three-run homer to center field against Seattle's Jason Vargas. "You see a lot of guys get mad when they swing at bad pitches. You just have to make sure it's a pitch you can handle.
"You're not always trying to hit a homer. Obviously you just want to drive the ball, so you make sure the pitch is in the zone."
Shelton said the Rays usually consider several factors when deciding to let a hitter swing away in those scenarios: the game's score and momentum, how he's hitting and swinging the bat, who's hitting behind him, what the opposing pitcher has done recently, and so on.
On top of that, there's the question of whether the manager trusts his hitter to stick to his pitch -- only his pitch, and only in that very small hitting zone -- when given the green light. If a hitter lacks the discipline to do that, he might make bad contact that results in an easy out, or worse, miss an opportunity for an easy walk that would prolong the inning and create more scoring opportunities.
"I think the biggest thing with guys is just making sure they don't get over-amped and try to do too much with that pitch," Shelton said. "You just have to make sure the barrel's out front. The most important thing is that you're ready to hit, that you never get beat by timing in that situation."
Tigers skipper Jim Leyland has found himself giving the green light now more than ever before in his career, and he has done so for a variety of reasons.
He's done it with slower hitters hoping to give them a chance to bash a home run or a double, freeing up first base, and giving him different ways to work in hit-and-runs or sacrifices in order to avoid station-to-station offense. He's also done it to try to get slumping hitters out of a funk by letting them hack away at what should be a more hittable strike than they'd find in other counts.
The Tigers have only put three balls in play on 3-0 counts this season, and two have gone for outs. Leyland had outfielder Brennan Boesch swing away on a 3-0 pitch against Rays pitcher James Shields on June 29. Boesch had hit a double in a similar situation earlier in the season, but it didn't work out against Shields, as he flied out to center field.
"I let Boesch hit, tried to give him a little confidence," Leyland said. "There's a lot of different schools of thought. ... He just didn't quite get it out far enough, but he hit it good."
In giving the 3-0 green light more often, the veteran manager has also learned something new about baseball: There's a substantial gap between telling a hitter to swing away and actually seeing him do so. Perhaps the conventional wisdom still rings true with most players.
"I think I've given [the green light] more since I've been in Detroit than in all my other years of managing combined," Leyland said last week, "only to find out that most guys don't swing on 3-0."
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry.