On Tuesday night, Chien-Ming Wang threw 7.1 shutout innings in Cleveland, holding the Indians to five hits and one walk. He struck out only three, but since he kept the ball on the ground, getting 14 ground outs and only five fly outs, it didn’t matter. Opponents can’t hit home runs if they’re pounding the ball into the dirt.

Sometimes, though, the lack of strikeouts can be a problem. Over the last three seasons, the typical American League pitcher has struck out about six batters per nine innings. In 2005 it was 6.16, and this season it’s 6.21. Despite possessing a fastball that can reach the mid-90s, Wang has only whiffed 3.24 batters per nine innings this season. This is a slight decline from his rookie year, when he fanned 3.64 batters per nine.

This relative lack of strikeouts leads directly to Wang’s inconsistent results. His prior start, against the Red Sox, was another strong outing, with only one run allowed in seven innings. The three previous starts, against Boston, Kansas City, and Detroit, were less successful, with 16 runs allowed in 17 innings.

In at least one of those starts, Wang’s June 1 outing at Detroit, he struggled with his usually strong control, walking three batters in four innings – this against a team that, despite it’s great success this season, is as resistant to talking ball four as any team in the circuit. But for Curtis Granderson, the Tigers don’t have a single player who, whatever their other offensive qualities, could reasonably be described as “patient.”

That accounts for one poor Wang start, but not for the seven other starts out of 15 in which he failed to record a quality start (six innings or more pitched with three runs or less allowed.)

The answer lies in Wang’s low strikeout totals. Pitcher strikeouts aren’t just a positive because they look good in the “Baseball Tonight” highlight packages or because of their ability to prevent things like sacrifice flies or advancing a runner on a ground ball (strikeouts prevent double plays too), but because they eliminate the role of luck in the outcome of an at-bat.

It’s a relatively new concept in sabermetric thinking, but it should have been obvious all along: Almost everything that is commonly thought of as the result of pitching is actually the province of defense. A pitcher can affect just a few aspects of what the batter does in any given at-bat. He can prevent him from making contact by striking him out, he can prevent him from making contact by walking him, and he can serve up a fat pitch and give up a home run.

Everything else that results from the batter-pitcher confrontation comes from the complex interaction between bat and ball. The pitcher supplies part of the equation in the same way the father provides half the DNA that goes into making a baby, but can’t be accorded the full credit or blame if the child goes to the White House or to Leavenworth (admittedly a thin distinction these days).

The batter supplies part of the remaining impetus for the outcome and the defense supplies the rest. Imagine two hitters, one batting against the Reds and the other against the Braves. Batter A hits a sinking liner to center field. The Reds’ center fielder is Ken Griffey Jr., whose legs just aren’t what they used to be, so the ball dunks in for a clean hit. Maybe Junior never even came close to it, so that no one watching the game has reason to suspect that, under different circumstances, the ball might have been an out.

Batter B hits the same sinking liner to center, but Andruw Jones is patrolling the big pasture for the Braves. He has better speed and reflexes, and perhaps he has the batter positioned better as well. The ball falls neatly into Jones’s glove. He doesn’t have to sprint or dive, so no one watching the game has reason to suspect that, under different circumstances, the ball might have been a hit.

In both cases, the outcome goes on the pitcher’s record.The pitcher for the Reds gives up a hit, and eventually, perhaps, a run or two. The pitcher for the Braves gets credit for having induced an out. It would be asking a lot of either pitcher to expect him to pitch to his defense to the extreme of directing the ball away from the poor fielders and toward the good ones.

Chien-Ming Wang can sink the ball better than most pitchers, so he has an inordinate say as to the results of each at-bat, but even given that power, he’s limited to getting grounders. He can’t induce grounders to Robinson Cano and Alex Rodriguez but not to Derek Jeter and Jason Giambi – not that Rodriguez and Cano are the standards for defense at their positions. It might be more fair to Wang to say that his control isn’t so good that he can escape being a ground ball pitcher in front of the Yankees infield.

That, as they say, is the rub. In a bestcase scenario, Wang is vulnerable to luck. On many days, the grounders induced by his sinking fastball will roll neatly into the fielders’ gloves. On some days, for reasons including the quality of his defense and just plain old disagreeable swings on the part of the hitters, they won’t.This is true for every pitcher, but Wang suffers more because he’s nearly half as likely to get a strikeout as the average hurler. That pitcher can diffuse a potentially disastrous situation by getting a batter to swing and miss. Wang’s only recourse is to try to get another ball to roll into the infield,which is tantamount to rolling the dice.

Until the day comes, if it comes, when Wang develops a strikeout pitch, he will continue to have good days and bad almost at random. Because the sinker limits the opposition’s best scoring weapon – the home run – he will sometimes have very good days, but very good seasons will remain beyond him.

Mr. Goldman writes the Pinstriped Bible for www.yesnetwork.com and is the author of “Forging Genius,” a biography of Casey Stengel.