The people who were watching with their eyes, not their hearts, saw it. The legacy player was inferior, inadequate. The uniform was the same. The guy in it was the same person. But he wasn’t the same player.

Not close.

In 2014, the Yankees deployed Derek Jeter almost daily at shortstop, though every metric and every scout concurred that his defense had become silver-haired, far from Gold Glove. The Yankees kept installing Jeter in the second spot in the lineup though the magic had left his bat — he had the ninth-worst OPS-plus of any qualified hitter (by the way, one of those worse than Jeter was DJ LeMahieu).

Why was Jeter used in this way?

Because the Yankees had put themselves in the worst position to transition from a legend. There was no obvious heir apparent, making it harder to justify sitting a historic player. Cito Culver was a wasted first-round pick in 2010. Eduardo Nunez never showed consistency or health, and was traded in April 2014. Dean Anna, Stephen Drew and Brendan Ryan were even worse hitters than Jeter was.

Also, ownership did not want to embarrass Jeter and potentially disenchant fans. Jeter wanted to play and hit second, and he had helped bring championships (plural) to the signature franchise and had been the face of the success and had conducted himself with grace and distinction on and off the field.

In other words, Jeter was a lot like Eli Manning.

“There are a lot of different dynamics that go into a decision like this,” said Brian Cashman, who perhaps more than anyone in sports understands this changeover, having in his three decades-plus with the Yankees (the last 21 as GM) helped to transition out Don Mattingly, the Core Four, Bernie Williams and Alex Rodriguez. “Where are you from the winning standpoint? Is the superstar on the way out still a massive contributor, still competitive, above average, average? Do you have internal replacements?”

In Geno Smith or Kyle Lauletta, the Giants have had their versions of Drew and Ryan. But the Giants invested the sixth pick in the 2019 draft on Daniel Jones, who was announced Tuesday as the new starting quarterback, moving Manning to the bench.

A franchise has to avoid being hijacked by the needs and concerns of a legacy player and how fans might react to perceived disrespect. The decisions can’t be about one star, regardless of how much collateral he’s accrued. Teams have to go hard in one direction or the other: playing to try to win now or playing to try to win later. Manning was offering neither path.

But the reality is that when Michael Corleone said in The Godfather, “It’s not personal, it’s strictly business,” of course it was personal to his character. And it is hard not to make these decisions personal. The Giants’ leadership — as surely as the Yankees’ with Jeter — cannot just ignore the historic value of the player, rings won, fan loyalty.

The 2014 Yankees missed a wild card by four games. Might they have made up that difference if they moved Jeter down in the lineup or played the defensively excellent Ryan more often? Who knows?

The 2019 Giants almost certainly lack wild-card hopes two weeks into a season. But at least they begin a process of finding out about their future. And the key really is getting the next guy right for the future.

The Yankees have kept winning throughout all the transitions because, in general, the next guy has been capable — and often much better than that. Mattingly gave way to Tino Martinez, for example. Mariano Rivera to David Robertson. After Anna/Drew/Ryan, the Yankees did a handoff from Jeter to Didi Gregorius.

Some of it was uncomfortable. The Yankees stuck a year too long with Bernie Williams and limited Kenny Lofton, who was better at that time, before moving to Johnny Damon the following year. Jorge Posada did not like how his catching role was taken away, but Russell Martin was better. A-Rod did not like his end game in 2016, but the rising presence of the righty might from Gary Sanchez and Aaron Judge made it sting less.

“We were able to transition with success,” Cashman said. “The worse is you rip the bandage off and whatever you do is inconsequential and not that good because you don’t have the right replacement. That makes the transition more difficult and more problematic and traumatic and adds to the turbulence.

“Great players are great because of their competitive nature and are usually the last to know and admit they are losing their skills. … If you don’t have an alternative that would challenge the throne, you are in a worse spot. Ultimately, we are charged with putting the best team on the field and there are a lot less challenges to deal with [if the next guy is a good player].”