What transpired Sunday with the Giants — Davis Webb and several other players who thought they were safe being cut — is a lesson on what happens when a new regime takes over. That regime wants its own players, is loyal to its own players and the only sure thing is change.

General manager Dave Gettleman and head coach Pat Shurmur inherited Webb, a third-round pick in 2017 of Jerry Reese and Ben McAdoo. During the spring and summer, Shurmur managed to say a few nice things about Webb, who was presumed to be the backup quarterback to Eli Manning. Shurmur, though, never endorsed that as fact, even as he gave Webb the second-team reps in training camp.

The new regime stated what it thinks about Webb by the action it took. Webb on Saturday made the initial 53-man roster but the Giants kept four quarterbacks, a sign something was brewing. The Giants tried to find a trade partner for Webb and when they could not, they cut him, leaving an eclectic mix of rookie Kyle Lauletta and 30-year old Alex Tanney as the quarterbacks behind Eli Manning.

Think of that. The Giants kept Tanney, a nondescript journeyman who has been signed and discarded by seven teams, and dumped Webb, an earnest 23-year old with a howitzer right arm.

Webb’s departure was part of a wild day of dealing by the Giants, who claimed and were awarded six players off waivers. That is stunning player movement, and an indication how lacking the new decision-makers viewed the talent on the roster. The Giants are coming off a 3-13 season and are purging nearly all remnants of that disaster. The new Giants, moving immediately to the 53-man roster, are kick returner Kaelin Clay, defensive end Mario Edwards Jr., defensive backs Antonio Hamilton, Mike Jordan and Kamrin Moore and offensive lineman Spencer Pulley.

The Giants had to make six corresponding moves to fit the new players onto the roster. In addition to Webb, they parted ways with veteran guard John Jerry, veteran cornerback William Gay, defensive lineman Josh Banks, tight end Jerell Adams and kick returner Hunter Sharp.

It does not appear as if the Giants have a legitimate backup quarterback. Lauletta showed plenty of moxie this summer, but, coming from an FBS school in the Colonial Athletic Association, it is a leap of faith to assume he could take control of the offense should anything happen to Manning. Tanney is a complete unknown — he last started a game in 2011, in college — in Division III. Keeping these two around and eliminating Webb, a youngster with a good attitude and definite physical skills, shows just how intent Gettleman and Shurmur are to build this team in their own image, with their own players. That Shurmur, a noted developer of quarterbacks, signed off on the release of Webb is all you need to know about what the Giants feel about Webb’s potential — especially considering the quarterbacks they decided to keep.

Webb, Shurmur said, was too “amped up’’ in his preseason debut, while Shurmur praised Lauletta’s calm demeanor. There was no way Lauletta would be sent packing. Keeping Tanney qualifies as a major upset. He is a product of Monmouth College in Illinois and kicked around NFL camps and practice squads for six years. He has appeared in one NFL game, with the Titans in 2015.

Webb was never quite the heir apparent to Manning, but Reese and especially McAdoo thought enough of the tall, strong-armed prospect to make him the 87th overall player taken in last year’s draft. The thought was Webb could develop into the next starter when Manning, 37, was finished. Gettleman and Shurmur watched Webb, liked his work ethic and his attention to detail but never saw great potential in him. When Lauletta was taken in the fourth round of the draft it was a sign the brain trust wanted another young quarterback to develop.

The thinking that the Giants bypassed taking a quarterback with the No. 2 pick in this year’s draft — they went with running back Saquon Barkley — had anything to do with Webb’s presence on the roster was faulty logic at the time and now proven to be completely misguided. The Giants loved Barkley more than they loved any of the quarterback prospects. It had nothing to do with Webb. Now, the Giants have nothing to do with Webb as well.