Longtime lurker...
It seems as though posters are arguing against one of two extremes when in reality the majority of individuals are more moderate in their respective positions.
Certain fans seem intent on stamping out what they perceive to be the Manziel "fanboys" who unabashedly felt that success in the SEC and a catchy nickname preordained Manziel to NFL superstardom at the expense of Brian Hoyer. I find this persecution to be rather quiotic, as I cant imagine many rational fans of the Browns and/or Manziel to have expected any player, regardless of pedigree, to step onto an NFL and dominate at the quarterback position. Conversely, there are certain Manziel supporters that feel as if many fans and the Browns organization itself has somehow concocted a scheme to ostracize Johnny, never allowing him the fair chance to succeed. Again, it defies logic to believe that any coach, front office personnel, or fan would implicitly compromise their livlihood (for coaches this is quantified by winnings, for fans it is their desire to support a winner) out of spite or some unfounded machonistic need.
From my perspective, I think that most rational individuals fall somewhere in between these two extremes. Manziel supporters by and large felt that Johnny had (has) the potential to develop into a quality NFL quarterback after progressing through the learning curve that nearly every quarterback....well, ever has had to master. More reserved Browns fans are hopeful that Manziel can succeed in Cleveland and acknowledge that he has certain skills that may be exciting, but too many heralded quarterbacks have come and gone throughout the years in Cleveland for them to have untempered enthusiasm for the latest golden-boy. Unfortunately, there do exist illogical individuals on both sides that rile up these more moderate fans and stoke the flames in favor or against whichever "faction" appears to be more substantiated at that time.
What we do know is that Johnny Manziel had a brutal first start in the NFL, approaching near-historic futility. I think that most of us would also agree that, thankfully, the overwhelming majority of NFL quarterbacks also struggled in their first start so all hope is not lost, yet. Of course the next milestone that all interested parties have set their sights on is Game 3, representing the last game of this season and a three game sample for Manziel. I'd also suggest that predictive power of the three game sample has not been historically strong for quarterbacks in like situations to Manziel's.
I surveyed a sample of current starting quarterbacks in the NFL that had relatively similar circumstances with regards to their first three starting opportunities. In reviewing the context of these experiences I took into account the year in which they debuted, their debut relative to their draft year, the pedrigree or "hype" surrounding them, and their role within the offense. For example, I dont find it as useful to look at Brady/Peyton from 15 years back, or Rodgers/Romo having the benifit of sitting for multiple seasons, or even Cam Newton/Luck who were expected to throw the ball 40 times a game and have the offense run through them from the onset. There were some players such as Matt Ryan and Russell Wilson that did come out of the gate and look solid, whereas other quarterbacks such as Jake Locker were omitted because they clearly have little future in this league and would only muddle our conversation.
In any event, I noted the following players and their respective performance through the first three starts or significant playing time of their careers. In order of the best debut performances to the worst...
Player--Comp%--TD/INT--Yds
Sanchez --59%--4/2--606
Cutler --59%--6/3--592
Shaun Hill --55%--6/3--537
Roethlisb. --61%--4/3--513
Brees --60%--3/2--504
Flacco --56%--1/2--450
Stafford --53%--2/5--598
Tannehill --53%--1/4--615
Fitzpatrick--54%--1/7--467
E.Manning-42%--1/4--423
Alex Smith-54%--0/8--351
You can notice a rather steep dropoff in production from Brees (arguably irrelevant data from 2001) to Flacco and the grouping below. What is clear to me is that the relative success, or lackthereof, of each player listed in that three game sample had very little predictive power in projecting their career success going forward. In fact, you have as many Super Bowl championships (3) from that top grouping as you do from the bottom grouping, with Stafford and Flacco still relatively young.
Now to be clear, Johnny Manziel's debut was worse than any of the aforementioned quarterbacks, arguably sans Smith & Manning. In addition, certain quarterbacks listed may have struggled on the field but clearly possessed physical NFL attributes beyond that of Manziel including the size and arm strength of Flacco, Manning, and Stafford. That being said, I think there is enough empirical evidence to suggest that Johnny's NFL obituary should not necessarily be written in December of his rookie season.
So, anyway..TL;DR...I think that the two opposing extreme viewpoints of Johnny are not truly indicative of how most rational fans feel. I think anyone foolish enough to suggest that Manziel could step onto an NFL field as a rookie and dominate should be taken as just that...a fool. I hope that folks can be a bit more forward thinking to realize that while Manziel was horrible in his NFL debut, there have been precadents set in which quarterbacks mastered the NFL learning curve after humbling rookie experiences.