ANAHEIM — Never underestimate the power of advertising.

The Angels suspect that an ad, of all things, might have contributed to their mysterious trouble hitting left-handed pitchers over the past several years.

The Angels have the worst batting average in the majors against lefties since 2015, which has been a well-chronicled head-scratcher. Throughout that time, the Angels’ best hitters, including Mike Trout, have been right-handed.

Months of study by the team’s analytics department concluded that a part of the problem might have been an ad on the center field fence, General Manager Billy Eppler said this week.

The ad had been encroaching toward the batters’ line of sight since 2012, moving to its furthest left position, closest to straightaway center, in 2015.

When the Angels returned home for this homestand on Tuesday, the sign – for the Pechanga Casino – had been moved to the right, clearing the fence in center field.

Eppler said he’s not sure moving the sign will make a difference, and he’d never heard a player complain about the placement, but the numbers suggested enough evidence to move it anyway.

“There was no downside in moving the sign,” he said. “We’ll see if there’s any upside or if this was just statistical randomness.”

Right-handed hitters Trout, Justin Upton, Albert Pujols and former Angels Ian Kinsler and C.J. Cron were all asked within the past month about any visual issues that might have affected performance against lefties in Anaheim, and none said they had any problems.

The numbers, though, say something unusual was happening.

Since 2015, the issue with left-handed pitchers has been more pronounced among the Angels’ right-handed hitters, and more so at home. And it’s not just the Angels, but the visitors, too.

Across the majors, right-handed hitters have hit .258 against left-handed pitchers and .250 against righties since 2015. That’s the expected platoon advantage.

However, during that same time at Angel Stadium, it has been the opposite. Right-handed hitters in Anaheim – the Angels and their opponents – have shown an 18-point reverse split, hitting .235 against lefties and .253 against righties.

From 2010-14, right-handed hitters had the normal split at Angel Stadium, hitting .249 against righties and .261 against lefties.

The Angels’ analytics department had been working at this for months. Once they began filtering the results, a pattern emerged, Eppler said.

“We started to notice a signal with the left-handers, more than just randomness, there was some kind of signal that kept showing up on left-handers that had certain release heights,” Eppler said. “We researched those heights and we came down (to the field) and got the optics on it. We thought there might be a contributing factor with one of the signs.”

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Angels get an optimistic glimpse of the future in win over Padres Eppler presented the issue to club president John Carpino, who said they could move the sign during the team’s most recent trip. When the Angels returned home on Tuesday, the sign was shifted the farthest to the right it’s been since 2012.

Trout, who debuted as a full-time player in 2012, has a reverse split at home throughout his career, but particularly since 2015. Over 2,254 at-bats since then, Trout has hit 48 points better against righties at Angel Stadium, but 17 points better against lefties on the road.

Over that same span, Pujols has a 52-point reverse split at home, but a six-point positive split on the road, covering 2,485 at-bats.

Cron is an interesting example because he played three years with the Angels and two seasons with other teams in that span. Over that entire period, he has a 79-point reverse split at Angel Stadium, but a 59-point positive split in all other parks. That includes 568 at-bats at Angel Stadium and 1,317 in other parks.

Now with the Minnesota Twins, Cron was asked last month if something in the background could have affected his trouble against lefties in Anaheim: “I don’t think so. If there is, I never heard a complaint about it.”