John Cena has done a lot of great things for the WWE and pro wrestling as a whole.
He's worked as the industry's top star for the better part of a decade, he sells more merchandise than anyone else, he's delivered in a ton of major matches and he's a great ambassador for the company.
At the same time, though, Cena has also hurt the WWE product in plenty of ways.
Whether by default or design, Cena and the booking of his character has been detrimental to the WWE on more than occasion, and in many cases, the effects of that can still be felt today.
Even though Cena has still, overall, done more good for the WWE than bad, it's hard to overlook some of the things he's been a part of that have had a negative impact on the company.
Here are 10 ways John Cena has hurt the WWE product.
In the summer of 2010, The Nexus debuted and quickly became one of the hottest angles we'd seen in the WWE in years.
That was until John Cena became involved.
When Cena became The Nexus' No. 1 foe, it didn't take long for the group to start falling apart, with things really starting to go downhill at SummerSlam.
Once Team WWE (which was really Team Cena) defeated The Nexus in the main event of the pay-per-view, the group of NXT rookies lost almost all of its credibility and never really seemed to fully recover.
Cena continued to be the main piece of The Nexus' major story lines, and ultimately, he would attack all members of the group and go on to defeat Wade Barrett in the main event of WWE TLC.
By that point, The Nexus was essentially done, and much to the surprise of no one, Cena was looking strong once again even though he had supposedly been "fired" earlier that year.
Had Nexus stayed away from Cena, there's no telling how big the stable would have come or how much success it would have had.
But I guess we'll never know.
It's understandable that John Cena's character is supposed to be a "superhero" who can overcome anything in his path.
But his no-selling has often gotten to be so ridiculous that it kills the realism of his matches.
I can recall seeing Cena getting attacked from behind with a chair by CM Punk, only to get up from it about 15 seconds later. I also remember him basically acting like nothing happened to him after he was dominated for 20-plus minutes by Brock Lesnar at Extreme Rules.
These are just a couple of examples in a sea of hundreds of them, though.
Cena is the king of taking multiple big moves only to kick out of them and going from zero to hero with his comebacks at the end of matches.
He no-sells far more often than he actually sells, and it kills the realism of his matches, which are usually very good otherwise.
John Cena has had a negative effect on the pushes of many up-and-coming superstars.
Take, for example, him beating Alberto Del Rio for the WWE Championship at Night of Champions in 2011, which was completely unnecessary.
Why did Cena "need" to win the title from ADR just a month after Del Rio had won it? Answer: He didn't.
Better yet, why on earth would Cena be booked to beat Dolph Ziggler in such a ridiculous manner on not one, but two straight Raws like he has over the past couple of weeks?
While we all know that it's not Cena who's booking himself, he just beat Ziggler two straight weeks after "The Showoff" hit him with everything and he hit Ziggler with just one AA each match.
When Cena does things like prematurely end a superstar's title reign or beat a rising heel clean two straight weeks, it's not doing any good for anybody.
Well, except for Cena.
If you do or see the same thing over and over again, it's going to start to seem redundant.
That's true in all walks of life, whether it be work, school or even pro wrestling.
Perhaps that's why seeing John Cena in the WWE's brightest spotlight for so long has gotten to be very repetitive and, quite frankly, very boring.
Cena has been the WWE's biggest star since roughly 2005, and during that span, no one has truly challenged him for his spot as the company's top guy.
"The Champ" deserves to be commended for that because a lot of that has to do with the fact that he's remained over and has worked his tail off to stay there.
At the same time, though, how long can a guy compete in PPV main events and top storylines before it gets old?
Cena has been involved in so many major angles and matches over the past seven or eight years that he's hogged the spotlight that other stars should get more of a chance to have.
As a result, it's been really tough for anyone to rise to the top of the WWE like Cena was able to do eight years ago.
John Cena has been involved in some absolutely atrocious storylines over the years.
Just in 2012, he was the centerpiece of that awful "embrace the hate" angle involving Kane and Zack Ryder as well as that terrible "AJ Lee scandal" that became painful to watch at times.
It's not like Cena is the one who's writing these angles. But these angles have often been done to benefit him.
The "embrace the hate" angle was meant to try to build up more sympathy for Cena. Meanwhile, the angle with AJ resulted in Cena getting a shot at the Money in the Bank briefcase (in the main event of WWE TLC, of course) and beating Dolph Ziggler clean two straight weeks.
The WWE is obviously going to continue to push Cena as a top star, but at times, the company's need to do that results in horrendous storylines that do nothing positive for anyone involved.
The Nexus, his WWE title feud with The Miz, "embrace the hate" and the "AJ scandal" are just a few recent examples of Cena's bad storylines resulting in Cena back on top.
One of the most infuriating things about the WWE was its insistence on putting John Cena in its pay-per-view main events.
From February 2012 to July 2012, Cena main-evented six straight pay-per-views. For 2012 as a whole, he main-evented nine total PPVs, despite being sidelined for Hell in a Cell.
That's absolutely insane, especially when you consider the poor quality of some of those main events.
While Cena delivered the goods at shows like Extreme Rules and Night of Champions, he also had atrocious main-event matches against Kane at Elimination Chamber, John Laurinaitis at Over the Limit and Big Show at No Way Out.
So, let's pose a question: Would it really have killed the WWE to have put other matches in the main-event slots at those PPVs?
Of course not.
But the WWE's insistence on giving Cena the PPV main event slot resulted in three laughable PPV main events in 2012 when other matches were far more deserving of closing the show.
It would take a very long time to compile a list of all the matches John Cena has won that he shouldn't have.
One recent match that immediately comes to mind is Cena vs. Brock Lesnar at Extreme Rules 2012.
This was Lesnar's first match back after his return last April, and he dominated Cena for essentially the entire match. Of course, that didn't stop Cena from turning into "Super Cena" and somehow winning the bout anyway.
In turn, this killed all of the momentum Lesnar had when he initially came back and has put a huge damper on his return since then.
There's no doubt that Cena should have lost that match, just like his team should have lost to The Nexus at SummerSlam 2010 and just like he never should have beat Alberto Del Rio at Night of Champions in 2011.
But when it comes to Cena, you can usually throw what "should" happen out the window because more often than not he's going to win major matches, even if the best booking is for him to lose.
Many have labeled John Cena as this saint who's such a great guy and does nothing wrong.
Yet, he's buried his opponents on more than one occasion.
One thing a wrestler should never do is bury the guy he's feuding with. The logic behind that is this: If your rival sucks so bad, then why even bother feuding with him?
Perhaps that's why it was disappointing to see Cena bury the hell out of Dolph Ziggler on Raw a couple of weeks ago, even using the word "push" and mocking Ziggler for taking so long to get to the main event.
It's hard to see the logic behind Cena burying another top star, but it's not just Ziggler he's done it to.
He's done it to others as well.
He verbally buried The Rock when calling The Rock out about his wrist notes in much the same way that he's physically buried so many other stars by defeating them time after time after time.
Cena buried The Miz too many times to count, and he did the same to The Nexus, Alberto Del Rio and plenty of others.
And it's safe to say that the man who is supposedly the WWE's top babyface shouldn't spend his time looking like a prick by burying the supposedly bad guys.
One of the worst things about John Cena is his alter-ego, which many of you know as "Super Cena."
Super Cena, of course, is the guy who, no matter how many obstacles are in his path, always overcomes them.
Whether it be in the middle of a match or some sort of angle, Cena always finds a way to overcome the odds and rise above whatever roadblocks may get in his way.
The problem is, it's grown to be really annoying.
There's nothing fun or exciting about seeing Super Cena essentially always come out on top, no matter how high the deck is stacked against him. Yet, that is the case about 99 percent of the time.
Cena is the WWE's resident superhero, and in a way, he's (perhaps indirectly) caused the WWE to constantly look for its next unstoppable babyface.
That's why guys like Ryback and Sheamus are following a Cena-like path right now, a path that sees them win about 90 percent of the time and lose only under shady circumstances.
It's fine for the WWE to want to build up its next top babyface, but those top baby faces should not be unstoppable like Cena has been over the years.
We want top good guys that have to scratch, claw and fight their way to the top for months upon months before getting that big payoff at the end of a lengthy storyline.
Unfortunately, Super Cena and the rise of the unstoppable babyface means that, more often than not, the good guys are going to already be on top.
Over the last year or so, the WWE Championship has been put on the backburner, and that's happened largely because of John Cena.
As noted in an earlier slide, Cena competed in nine pay-per-view main events in 2012.WWE Champion CM Punk, on the other hand, competed in just three.
Two of those main events involved Cena, while the other took place only because Cena was recovering from elbow surgery and couldn't compete in the match.
It's a borderline travesty to think that the WWE's most prestigious title took a backseat to whatever Cena was doing, no matter how much more entertaining what Punk was doing at the time may have been.
But Cena's main-event hogging didn't just affect the WWE Championship. It affected the World Heavyweight Championship as well.
Want to know how many times the World title was defended in a PPV main event in 2012? Zero.
So, the PPV main event scoreboard reads something like this:
John Cena: 9
WWE Champion CM Punk: 3
World Heavyweight Champion (multiple): 0
Way to have your priorities straight, WWE.
Drake Oz is a WWE Featured Columnist for Bleacher Report. Follow him on Twitter!