As recently as 2003, Mike Trout’s whiff rate right now would qualify as a record-breaking pace.

The Angels center fielder has 42 strikeouts in 35 games entering play Sunday, a 194-strikeout pace over a full season. Until Adam Dunn whiffed 195 times in 2004, Bobby Bonds’ 189 strikeouts in 1970 held baseball’s long-standing record.

Now, though, Trout’s strikeout pace would only tie for 15th-most all-time. That’s because the 15 individual seasons featuring the most strikeouts in MLB history have all occurred in the last decade, and the five seasons with the most whiffs have all occurred in the past five years.

Hitters are clearly striking out much more than they used to, and sabermetrics can help us determine what that means.

First, it’s important to note why strikeouts are bad, which is fairly simple. Outs are generally the worst possible outcome in a plate appearance, and every strikeout is a guaranteed out, barring a rare dropped third strike. Every ball that is hit into play has a reasonable chance of not being an out.

Some balls in play have higher probabilities of not being outs than others — line drives are better at resulting in hits than grounders and grounders are better than flies — but putting the ball into play is the only way to get a hit. (Other than by hitting a home run, which is not considered in play.)

For the vast majority of major-league hitters, between 25 and 35 percent of all balls hit into play will fall for hits. And that’s where the strikeouts come in. For every 10 additional strikeouts a regular player amasses in a full season, he is giving up something like six points on his batting average.

Ignoring walks, imagine a typical major-league hitter with, say, 500 at-bats and 15 homers in a full season. If that hitter struck out 100 times, a little better than the major-league average rate, his expected batting average would be .261.

But if he struck out only 50 times, his expected batting average would rise to .291. If he struck out 150 times, it’d be .231.

It’s rarely so simple, but Trout’s recent slump is a product of batting average on balls in play naturally normalizing. Over the season’s first month, the 22-year-old’s high strikeout totals were getting disguised as 42 percent of his balls in play were falling for hits.

Since May started, that number has dropped to below 10 percent, and with it, his batting average has dropped from .327 to .275. Neither figure will stay that low, of course, but it’s also extremely unlikely that Trout will be able to hit in the .320 range if he continues to strike out like this, 40 percent more often than in 2013.

But strikeouts are increasing across the board, not just in extreme cases. Every year since 2008, MLB has set a record for the most league-wide strikeouts. This year, hitters are striking out 20.5 percent of the time — about twice as much as 60 years ago.

Hitters can be successful while striking out a ton, but those have almost exclusively been power hitters. For example, for his career, Mark McGwire struck out 20.8 percent of the time, right around Trout’s career rate through roughly 2 1/2 seasons.

The game has changed. Trout is a great example of how, but even he needs to change back some to continue the success he had in 2012 and 2013.

Contact the writer: pmoura@ocregister.com