Give John Idzik credit.

The former Jets general manager had a vision of sustainable success he thought he could achieve with shrewd spending and deliberate negotiating tactics. But in the end, his flawed logic and faulty practices cost him his job. Now it's up to new GM Mike Maccagnan to see his own plan through.

But there is one benefit to Idzik's stingy ways. Maccagnan and new coach Todd Bowles have about $50 million in available cap space. The question is: Will they know what to do with it?

There are several issues the front office needs to address this offseason, but none bigger than cornerback. Among Idzik's biggest miscalculations were assuming Dee Milliner (Achilles) could stay healthy in 2014 and that journeyman Dmitri Patterson was starter material.

The new Jets regime can't make the same mistake when it comes to Milliner. He and Dexter McDougle (ACL) are coming off injuries, so it's unclear how productive they'll be this season. For that reason, the Jets must find upgrades. The good news is there's plenty of cornerback talent available, starting with former Jet Darrelle Revis and former Seahawk Byron Maxwell.

Revis, a four-time All-Pro, is coming off a Super Bowl championship with the Patriots, but he'll likely play for the highest bidder in 2015. New England still controls his rights for this season, but there's no chance it will bring back Revis at a $25-million cap hit. The Patriots, however, could try to renegotiate Revis' contract to try to keep him.

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As the marquee free-agent corner, Maxwell is sure to fetch top dollar. If the Jets get priced out, they could turn their focus to former Jet Antonio Cromartie, who spent 2014 playing for Bowles, the Cardinals' former defensive coordinator.

The Jets also are interested in former Texans cornerback Kareem Jackson, according to a source. If there's one person who knows Houston's roster, it's Maccagnan, who spent the previous 15 seasons with the organization. Jackson may not have as high-profile a name as some of the other cornerbacks, but he has youth (26) and versatility on his side. He can play outside and in the slot, qualities that could be attractive to the Jets, who are looking to part ways with Kyle Wilson.

According to a source, the Jets also plan to meet with former Eagles cornerback Cary Williams.

Of course, there also are major questions at quarterback, centering around whether Geno Smith should remain the starter in Year 3. But it's even more crucial that the Jets find an experienced lineman to help protect their quarterback and clear holes for their running game. With free-agent guard Willie Colon unlikely to return, Nick Mangold and D'Brickashaw Ferguson a year older (both are 31) and instability at left guard, Maccagnan can't afford to walk away from free agency empty-handed.