After Carlos Delgado hit two home runs in a game against Atlanta earlier this season, he made the somewhat curious decision of refusing a curtain call from the Shea faithful. Delgado said he’d only received two curtain calls before, for his 400th home run and after a four-homer game, and that his performance against the Braves simply did not merit one. It appeared that the choice came from pride — if not arrogance. Perhaps Delgado sensed in the cheers a bit of pity, as if the crowd was being extra kind to an aging player it knew would not have many games like this again. While Delgado appears to see himself as the titan he once was, the fans see someone else wearing no. 21.

Delgado and Mets fans are both right. Two different Delgados have been taking the field for the Mets this season: the one Delgado sees in the mirror, and the one the fans think they see. They even make scheduled appearances.

The 35-year-old Puerto Rican, who is in the midst of a season that would make Rey Ordonez wince, has a rather drastic split — not home versus away, or right versus left — but a seemingly useless statistic: day versus night.

Over the last four years with the Mets, Delgado’s night batting average has been worse than his day average, and the split has been widening steadily. This year during the day, he’s been the slugging Delgado of old — .302 AVG/.371 OBA/.603 SLG, compared with a putrid .174/.258/.198 at night going into last night’s game. Last year, he hit a solid .288/.379/.509 during the day, but just .245/.312/.421 at night. What can this split possibly tell us — or more importantly, can it offer a solution — for Delgado’s batting woes? Is it harder to see the ball (and hit it) at night, and, if so, is this a part of Delgado’s problem?

I’m not ready to declare that Delgado has eye problems based on day/night splits. But one would have to think that, logically, it’s a bit more difficult to see the ball at night than in the day, and that a player with graying hairs might have a greater degree of difficulty seeing the ball in later games. Age is a real thing, not just a number, lest we forget.

According to Baseball Reference, major league batters hit .269 in 51,611 at bats last year during the day, and .267 in 116,172 at bats at night. Pretty similar. It allows for variation among individuals, but it’s fair to generalize that players with average vision should hit, and tend to, about the same day and night.

I’ve conceived a metric called Vision%, which simply measures night batting as a percentage of day batting, with 100 being equal dexterity at night and during the day, with the assumption that, all other things being equal, the average player will see and hit similarly at both times. For instance, if Player X bats .294 during the day, but .252 at night, his Vision% is 86. Moves of a few points in Vision% can mean huge jumps — chiefly because players hit about twice as many times at night.

Delgado’s Vision% has been on a downward trend since before he came to the Mets — from 97 in 2005, to 90 in 2006, to 85 last year, to this year’s awful 58. Now, one would expect normal variation in player’s stats, but Delgado’s is a downward slope. And it’s not just the relative splits that are problematic. Alex Rodriguez hit .340 last year during the day, and just .300 at night. But he hit .300 at night.

Delgado’s issue is that his night production simply isn’t good enough to be able to tolerate a lower Vision%. David Wright, for instance, had a Vision% of 80 in 2004, which went up to 93, down to 90, to 89, and then up this year to 107.

But Delgado shows a clear trend, and a discouraging one, at that. If this is Delgado’s problem, though, what’s the solution? Laser eye surgery? Well, maybe.

Matthew Namee wrote an article on this topic in 2004 in the Hardball Times. He wrote of his research on the histories of 17 players who had laser eye surgery beginning in 1996, from Al Martin to Wade Boggs and Bernie Williams. What he discovered was that in the year before the surgery, the players hit a combined .277/.364/.456. In the next year, they hit .282/.366/.491. In addition to small but traceable increases in BA and OBA, Namee found a 35-point jump in SLG. Furthermore, when you exclude the seasons of three of those players (Jeff Bagwell, Larry Walker, and Bernie Williams) who had fantastic seasons before the surgery (and, as Namee notes, would probably have hit a bit worse the next year anyway), the jump goes from an average .413 SLG to a .468 for the remaining 14 players.

Frank Catalanotto, one of the players who underwent the surgery, was quoted in Namee’s article as attributing much of his problems in 2002, when he hit .269 following a .330 campaign, to poor vision. “For that whole season of 2001, my vision was great,” he said before the 2003 season. “Then, last year in April I noticed things weren’t as clear anymore … In day games, it was fine, but in night games, it was just a little blurry. I couldn’t really focus as well. I just wasn’t picking up the spin on the ball.”

The year after the surgery, he rebounded to hit .299.

Are Delgado’s struggles solely attributable to eye problems? Probably not. But is it at least reasonable to think that these drastic splits could be symptomatic of eyes not quite as sharp as they once were? Yes. Maybe a little eye work could salvage Delgado’s season — along with the Mets’ hopes of scoring a few more runs. Right now, when the sun goes down, he’s hitting as well as a blind man anyway.

alexbritell@gmail.com