I believe that Manziel needs more time to prove to everyone that he is in fact a good player and not just a "one hit wonder" so to speak. Manziel's lukewarm preseason performance against players who were sub-par at best should be proof enough that he needs more time to master his craft before the Browns put him back on the field.
During the procession of a match, coaches have the weight of the game and the expectations of their fans on them. In the situation where he had to send Manziel back to the bench, no one can blame him. It is his choice based on the condition of the player and context of the game, he had to make a quick and informed decision.
Mike Pettine, coach of the Cleveland Browns can send Manziel back to the bench any time he feels it is in the team's best interest. He is the coach, he is paid on a professional level to do his job. The people of Ohio, or any Cleveland Browns fans, should trust his judgement calls.
Mike Pettine, being a coach, knows the strategy he is applying in the team. It is obvious that a coach will start to make some change after the results are not coming as expected. It was a total disappointment to lose a game with such a huge difference in score. After losing 30-9 to Pittsburgh
Steelers, anyone would think of bringing in some new talents and click certain tactics that will bring good result in next game. It time to think after the club lost for the fifth consecutive time and everyone should expect some changes in the team. And, it should be the coach who should act upon.