SANTA CLARA — Stephon Gilmore is not coming to rescue the 49ers’ cornerback unit.

So why did the Carolina Panthers acquire him for only a 2023 sixth-round draft pick Wednesday from the New England Patriots, when the 49ers clearly have depth and performance issues at cornerback?

Here is an educated guess, or make that four guesses:

1. CAROLINA HOMECOMING

Before we get to the root of all professional deals — big-money business — let’s take into account that Gilmore was born 30 minutes outside of Charlotte, North Carolina, and he played college football at South Carolina. Perhaps a Carolina homecoming is how the 31-year-old wants to close out an accomplished career. The Panthers are moving their headquarters in 2023 to his native town of Rock Hill, South Carolina.

Another enticement: The NFC South-leading Panthers (3-1) have an imposing defense that just got stronger.

Bill Belichick said the Patriots and Gilmore had a “mutual parting,” indicating to me that Gilmore got some say in where he could go, presuming a suitor ponied up to the Patriots’ asking price (after a morning revelation he would otherwise be released).

2. MONEY MATTERS

Gilmore and the Patriots couldn’t agree financially on a new deal, so it’s no surprise he lands with a Panthers franchise that has the second-most salary cap space ($19 million). Scheduled to make $7 million in below-market-value salary with the Patriots, Gilmore reportedly was seeking twice that in his next deal, and the Panthers can afford a $5.8 million cap hit this year for him.

The 49ers have $4.36 million in salary cap room, according to the NFL Players Association’s latest figures. Of course, flexibility always exists if a team really, really wants someone.

With next year’s salary cap expected to balloon $30 million (to $208 million), the 49ers need to budget for extensions for drafted players such as Nick Bosa, Deebo Samuel, Dre Greenlaw and Mike McGlinchey. Their pending free agents include starters Jason Verrett, Laken Tomlinson, D.J. Jones, Raheem Mostert, K’Waun Williams and Jaquiski Tartt.

Also factoring in financially are some hefty cap figures next season, all of which could be addressed in some ensuing fashion: Arik Armstead’s $20 million, George Kittle’s $16 million, Trent Williams’ $14 million, Jimmie Ward’s $13 million, Mike McGlinchey’s $11 million and, of course, Jimmy Garoppolo’s $27 million.

This wasn’t about preserving draft picks if all it took was a 2023 sixth-rounder. (And, hey, maybe Belichick is burnt out from negotiating with the 49ers on prior Jimmy Garoppolo talks.) The 49ers don’t have first-round picks in either of the next two drafts, but they do have an extra third-round selection next year by virtue of former defensive coordinator Robert Saleh’s hiring as the New York Jets’ coach.

3. HEALTH MATTERS

The injury bug is already impacting another 49ers’ season. They’ve lost Mostert and Verrett to season-ending injuries, and a constant wave of issues test their depth weekly.

So, do you really want a 31-year-old cornerback coming off quadriceps surgery who hasn’t practiced all year, skipped training camp and could need a couple of weeks to get into football shape to join a team that looks much more than one All-Pro cornerback away from true contention?

The 49ers have vowed to mitigate their injury risks, especially when you consider their 2019 high-priced acquisitions of injury-prone Dee Ford and Kwon Alexander. After the conclusion of last season’s injury barrage, Kyle Shanahan and John Lynch noted they’d looked harder at players’ health backgrounds and weigh the risk.

4. CORNERBACK LOW PRIORITY

This franchise’s defensive philosophy is to invest heavily in the defensive front seven, which it has done, leaving the secondary in a perpetual prove-it state.

No way should there ever be another Nate Clements-type signing (eight years, $80 million in 2007).

The 49ers considered it a coup this past spring that they re-signed their cornerbacks (Verrett, Williams, Emmanuel Moseley, Dontae Johnson) on budget-friendly, short-term deals. Verrett’s one-year gamble backfired on him as he was injured in Week 1, but the 49ers likely will try re-signing him again for next season (to a fourth one-year deal in as many years).

The 49ers also spent, for the first time in the Shanahan regime, two draft picks on cornerbacks. Neither Deommodore Lenoir nor Ambry Thomas played a defensive snap in Sunday’s loss to Seattle, by the way.