September 13, 2015 - East Rutherford, New Jersey, USA - Cleveland Browns quarterback JOHNNY MANZIEL (2) throws the ball away under pressure by New York Jets defensive end LEONARD WILLIAMS (92) during the NFL game between the Cleveland Browns and the New York Jets at MetLife Stadium in East Rutherford, New Jersey. The New York Jets won 31-10. Credit: Courtesy of TNS

Cleveland Browns quarterback Johnny Manziel(2) throws the ball away under pressure by New York Jets defensive end Leonard Williams (92) during the NFL game between the Cleveland Browns and the New York Jets at MetLife Stadium in East Rutherford, New Jersey. The New York Jets won 31-10. Credit: Courtesy of TNS

Johnny Manziel should be the Cleveland Browns’ starting quarterback for the rest of 2015, regardless of Josh McCown’s health and availability for Sunday’s game against the Tennessee Titans and Manziel’s performance in that game and beyond.

The reasoning is rather simple.

Cleveland spent a first-round pick on the 2012 Heisman Trophy winner and it needs to find out whether Manziel will be gold for an organization that has been looking for their franchise quarterback since 1999 or if he will be pyrite.

Manziel was originally the backup to McCown all throughout training camp and leading up to the Browns’ season opener against the New York Jets on Sunday.

But late in the first quarter, McCown sustained a concussion while diving for a touchdown on a play that ended up being the complete opposite of everything John Elway’s helicopter play was in the 1998 Super Bowl.

McCown fumbled inches before crossing the goal line and suffered the concussion that could potentially keep him out of Sunday’s game.

Into the game came Manziel, whose performance oscillated between dynamic and dull over the final three quarters.

There was his 54-yard laser throw to Travis Benjamin for a touchdown on his first series and the 14-yard scramble for a first down in the fourth quarter. He also had two 20-plus yard runs that got called back due to penalties.

But there were many dull moments too, such as the off-target short pass to Brian Hartline that was intercepted and the two strip-sack fumbles late in the game.

It was not necessarily a good showing but it was progress, considering the former Texas A&M sensation was nothing short of egregious in the two season starts he made for the Browns late in 2014.

After coming to terms with that fact that the callous preparation and backyard-like play style that thrust him into fame during his two collegiate seasons would not work against NFL defenses, Manziel made offseason changes.

He checked himself into rehab, worked with private coaches — including ESPN’s Jon Gruden — and improved his film study habits.

The Browns’ coaching staff had praised his progression, which was displayed at times against the Jets, but they were content on McCown being their starter.

The logic behind wanting to start the veteran — who inked a 3-year, $14 million deal in February — is understood.

Let the 36-year-old veteran, who has played for nine different NFL teams since being drafted in 2002, act as a stop-gap quarterback in 2015 (and maybe beyond) to fill the vacancy while Manziel’s development persists or they locate another guy they think could be their franchise quarterback.

McCown had looked good in camp and especially on the first drive against the Jets but his ceiling — as well as the Browns’ — is low.

Even if McCown played out-of-this-galaxy good in 2015, Cleveland still has a swiss cheese-like run defense, a receiving corp that lacks reliable talent and no starting running back.

If every domino fell in place with McCown at the helm, this Browns team would have, at best, been 7-9 or 8-8 — which would likely not be good enough to make the playoffs but rather good enough secure a middle-of-the-road draft pick.

Due to his age, McCown is nothing more than a short-term plug for the gaping hole that the Browns have historically had at quarterback.

It’s not that the Browns should just give up on 2015 and start Manziel, but the organization needs to see what type of signal caller the 2014 first-rounder can be.

He’s exhibited enough progress in camp, preseason games and against the Jets to deserve a shot at proving himself.

Backing up McCown could benefit Manziel, but the best way to see if the work he has put in can translate to NFL success is to let him play, not hold a clipboard.

He will struggle by missing opening receivers, throwing picks and fumbling. But he will probably throw more passes that resemble the 54-yarder to Benjamin and scramble for more first downs.

By playing him in 2015, the coaching staff will have a large sample size to know if improved Manziel is good enough to be their franchise quarterback.

If not, they will have to continue their search. Maybe that search will end with some guy named Cardale Jones.