Tom BradyFOXBORO, Mass. — What would the Patriots do without Tom Brady? They almost found out the hard way on Wednesday.

About halfway through the Patriots’ joint practice with the Buccaneers, Brady had his left leg rolled up on by tackle Nate Solder. The tackle’s momentum sent Brady to the ground, clutching his knee awkwardly in pain. After spending a few moments with the training staff, Brady did return for five snaps, including three completions on three passes, but something still wasn’t right and he headed off the field for the rest of the day.

Now, a few hours removed from the rampant rumor and speculation that immediately surrounded the injury, it appears that it’s nothing “serious” and that the quarterback could even practice on Thursday. But after a collective scare like that, there’s no helping wondering what the Patriots would do in case No. 12 ever really went down.

The quarterback depth chart is pretty simple at this point. It theoretically reads something like: “1. Tom Brady 2. Oh no, we’re screwed.” But, realistically, folks know it falls in line like this: 1. Brady 2. Ryan Mallett 3. Tim Tebow. There’s no telling whether Tebow even makes the final roster — the situation is still very much up in the air — but situations like Wednesday definitely reinforce the importance of keeping a third quarterback. But plugging either player in and expecting a smooth transition into the Patriots’ system is ludicrous.

The Patriots’ offense is complex, even for a veteran quarterback, andneither Mallett nor Tebow — nevermind most of the quarterbacks around the NFL — could carry even half the load that Brady does. And for all the Matt Cassel apologists out there who will point to 2008 and say that everything is going to be alright, let’s not forget that he was throwing to Wes Welker and Randy Moss out there and not a bunch of newbies like this year’s group. Neither quarterback has quite the experience of Cassel either.

When Cassel took over the offense in ’08, he was entering his fourth year in the system, meaning four years to learn under Bill Belichick and behind Brady. This year marks Mallett’s third preseason with the Patriots, leaving him still a little green and underdeveloped, and while Tebow enters his fourth NFL season he’s still spent barely two months in New England’s offense so far. Neither has shown anything resembling consistency or reliability during training camp either.

Mallett has enjoyed his moments in camp, connecting on a few long passes with the likes of Aaron Dobson and Kenbrell Thompkins from time to time, but, on the whole, he’s still a very raw player. The developmental flaws that teams harped on Mallett for ahead of the 2011 draft still exist, as he continues to struggle with accuracy and touch passing. Mallett’s deficiencies were on display in the Patriots’ first preseason game, too. He completed just nine of 18 passes on the night before coming off with a head injury, but he missed a few easy looks, including a deep ball to a wide open Josh Boyce down the middle, which can only enhance concerns about him running this offense full-time.

As for Tebow, he wasn’t any better. The wonder boy had struggled with accuracy and decision making all camp, and his general ineptitude was apparent on Friday night, too. He continues to underthrow receivers on the regular and can’t seem to get through his progressions quick enough, which leads to sacks far too often. If there are hesitations about Mallett running the Patriots’ offense, then Tebow must be labeled with a bright-red STOP sign. That’s not to say he couldn’t be successful in a specially-built package, but it’s doubtful Belichick wants to implement an entirely new offense to run weekly.

There is still potential with both Mallett and Tebow. Neither is a lost cause and both can definitely contribute for the Patriots, if need be. But, with the Super Bowl expectations constantly hanging overhead, there’s no chance the Patriots can get anywhere near their ultimate goal with either.

It’s Brady or bust, and, fortunately for the Patriots at least, they don’t have to ask “what if” anymore.

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Photo via Twitter/@SteveB7FSG