There is a chance fourth-round selection Brock Vereen will earn his way into the Bears defensive starting lineup come the end of August.

There is a chance Shea McClellin will thrive in his new role as strong-side linebacker, playing against opposing twos and threes for most of the summer.

There is a chance the new additions at defensive end – Allen, Houston, Young…etc. – will wreck havoc in Bourbonnais and throughout the preseason.

There is a chance the Marquess Wilson will solidify the third wide receiver spot and complete the best receiving corps in the sport.

There is also a chance none of it will matter. A strong chance. Because if Jay Cutler turns the wrong way on his knee during 7-on-7s or Matt Forte takes an awkward shot to the ankle or Brandon Marshall pulls up running through the seam, it will be that moment and nothing else that defines this summer for the Chicago Bears. NFL training camp has become a war of attrition, survival of the fittest, Thunderdome.

It has become a month-long breath hold for every die hard in the league.

Where must the Bears be healthy heading into a 2014 season as one game, one loss might be the difference between a division title and failure to make the playoffs? I shall tell you now. As a note, these are not the only positions where an injury would weaken the roster. But they are positions wherein injury could prove especially debilitating and perhaps ever cost games.

QUARTERBACK

Be wary of the Josh McCown Delusion –  the belief that Marc Trestman can turn any journeyman QB into a winning player. On the surface Jordan Palmer and Jimmy Clausen are not remarkably different players heading into the summer of 2014 than McCown was heading into the summer of 2013. (I wrote last year that McCown might have been the 2013 roster’s biggest question mark.) But every golfer knows you rarely chip in from the same rough twice. If Cutler misses any bulk of time, don’t expect a repeat of last year’s results.

RUNNING BACK

Matt Forte in Marc Trestman’s offense is, quite possibly, more valuable than any other starting tailback in the game. His ability to not only carry the load in the run game but provide exceptional protection for the quarterback while being a lethal threat in the passing attack made him one of the two or three most versatile and dynamic backs in the NFL last year. The Bears have some talent behind Forte at RB but they don’t have a player as good at any of those three elements, let alone adequate at all three.

WIDE RECEIVER

Here’s what I don’t think fans understand about Brandon Marshall and Alshon Jeffery: they are unique, exceptional talents. They are not the type of receivers Peyton Manning, Aaron Rodgers and Tom Brady can rotate in and out of the lineup. (Okay, our shorty, speedy guy is injured…go get that other short, speedy guy we have!) They are not successful because of a talented quarterback or dynamic scheme. They would be talented with me calling the plays and my mother throwing the passes.

The reason the Bears offense is one of the best in the sport is because it is rare for an organization to have two such talents on the same roster. (See: 2012 Atlanta Falcons) Losing one can have a demoralizing, mediocrity-inducing effect. (See: 2013 Atlanta Falcons) This is the reason I rank Cutler the most important Bear to keep healthy and Marshall and Jeffery second and third. The pairing of these two players is what makes this offense go.

TIGHT END

Martellus Bennett is one hell of an interview. He’s also the only pass-catching threat the Bears have at tight end. Bennett isn’t Jimmy Graham but his ability to take up the middle of the field opens the outside for the above receiving duo in the league and his presence in the red zone is beyond invaluable. Losing Bennett for any significant period of time will render tight end to a block first catch passes later position as Mulligan and Rosario are little more large bodies with hands and won’t worry opposing safeties for more than a few seconds.

DEFENSIVE END

Defensive tackle and secondary were addressed over draft weekend and in the wee small hours of the free agency morning. But Phil Emery’s big ticket, big money items were acquired to rush the opposing passer, most notably Jared Allen and Lamarr Houston. Yes, Mel Tucker will be applying a more varied, more aggressive defensive style. No, the Bears can’t expect to suffer the slings and arrows of the NFL’s injury epidemic on that side of the ball once again. But look at the names below Allen and Houston on the DE depth chart and you’ll understand how important it is to keep these two individuals healthy:

Without Houston and Allen healthy, it won’t take long till I’m reading emails complaining about Shea McClellin’s inability to be an every down defensive end.

The drop from safety starter to backup is minimal. The sooner Kyle Fuller gets onto the field full time, the better he’ll ultimately become. There’s a bunch of capable if not extraordinary fellas at linebacker and the offensive line is not only talented, they’re deep almost across the board.

These positions, lifted above, are the irreplaceable core of the Bears 2014 roster. With them on the field, they are title contenders. Without them, they’re a question mark each week.