By Peter Gleason

As Eagles fans trudge to the Linc tomorrow night for the Birds game with the Giants, it might be useful to point out that Philly’s season is essentially over and the Giants might make it to the Super Bowl.

On the backs of their great defense.

Which sucked in 2015.

Which proves that you can improve using free agency.

If you have smart guys making decisions in the front office and not children like Howie Boy Roseman!

Fresh off a huge victory in which the Giants held the vaunted Cowboys to just seven points, Big Blue’s defense held MVP candidate Matthew Stafford and the Lions to just six points on Sunday for yet another critical win for a team that looks playoff-bound. And, on the strength of this defense, the Giants could maybe even make some noise when they get there.

Make sure you remember that in March when media pundits and team execs alike seemingly come out of the woodwork to make sure we all know that spending sprees in free agency supposedly never work.

Somebody forgot to tell that to Damon Harrison. And Olivier Vernon. And maybe most importantly, Janoris Jenkins.

The Giants spent well over $100 million in fully guaranteed money to bring in all three of those players. And a funny thing happened: The moves paid off.

In one year, with the same coordinator and mostly the same cast of characters around them, the Giants defense has gone from being one of the laughingstocks of the league to arguably the best unit in all of football. Forget Jordy Nelson: Maybe the Giants defense should win the Comeback Player of the Year award, since this unit has seemingly come back from the abyss.  

How bad was it? We’re talking about a defense that ranked dead last in both points and yards allowed per game last year (27.6 and 420.3, respectively). 

The propaganda we’ve been fed for years, in some part from certain teams that don’t like to spend money, is that you can’t “buy a championship.” Maybe not, but it sure looks like you can buy a defense. A darn good one.

That’s not to say spending like a drunken sailor in free agency is a foolproof plan. It’s not. The Redskins proved that on an annual basis last decade. 

It’s also not like the Giants’ trio of free agent defensive additions aren’t getting any help. Second-year safety Landon Collins has had a breakout campaign and deserves to be in the discussion for Defensive Player of the Year. Rookie cornerback Eli Apple has really come on as of late, making it appear as if the Giants have nailed their high picks of defensive back in the past couple of drafts. Those guys, and others like Jonathan Hankins and Jason Pierre-Paul (before his injury), have certainly been a big part of the defensive turnaround as well.

Still, there’s no denying the impact that the Giants’ big money additions have had on this defense.  

Harrison is one of the best run-stuffing defensive tackle in the league, and it all starts there for this defense. Vernon is a stud against both the run and the pass and has provided a layer of toughness and leadership that has rubbed off on the rest of the unit, all while playing through a bad wrist. Jenkins has been one of the best cover corners in football, totally eliminating Dez Bryant last Sunday night as the Cowboys limped to a 1-15 showing on third down.

So, what are the lessons here?  

“You need to understand and identify what your team needs and then have an eye for it,” longtime Tampa Bay Buccaneers defensive tackle and current ESPN and SiriusXM NFL Radio co-host Booger McFarland told me recently. “When you spend in free agency, make sure you get young players on their second contract with a lot of upside. A lot of issues happen when people overpay for guys on their third contract. The Giants got three guys in the prime of their career and still relatively young. These guys are all still in their mid-20s.”

Like any part of the player evaluation process, free agency is far from a sure thing. You never really know for sure how a new player will adapt in your scheme, locker room and city. That’s why some teams are hesitant to dive into free agency. They feel like they are paying heavily marked up retail prices on items they aren’t very familiar with.

While that reluctance is somewhat understandable the Giants are proving this year that sometimes in life, and in football, you get what you pay for.