Make no mistake about it, the NFL has evolved into a passing dominant league. The rule changes that have gone into effect in recent years make it easier than ever to throw the ball, and we've seen quarterbacks and receivers put up numbers like never before as stat sheets look more and more like those you'd see in video games rather than real life.

As the new NFL has taken shape, it seems like the San Francisco 49ers have flirted with the idea of slowly changing their power running attack into more of an air assault. The flirtation looks to have grown more serious this season, as players like Stevie Johnson and Brandon Lloyd were added to give the team additional targets to go along with already impressive names like Michael Crabtree, Vernon Davis and Anquan Boldin.

Despite the additions and possible ideas to alter their philosophy, I'm here to make the prediction that the 49ers flirtation with throwing the football will never materialize into anything significant (at least not in 2014 anyway).

Here are five reasons the 49ers will stay with a ground centered attack this season:

1) The offensive line is built to run

A common misconception around the league is that the 49ers have an elite offensive line. The truth of the matter is San Francisco has a strong run blocking unit that struggles with pass protection. Need proof?

Since 2011, the 49ers have been in the bottom six in the league in sack percentage every season. 49er quarterbacks were sacked on 8.9 percent of their drop backs in 2011 (6th worst), 8.6 percent in 2012 (3rd worst) and 8.6 percent in 2013 (4th worst).

On the flip side, they've been in the top 10 in the league in yards per carry in 2012 (5.1, 3rd) and 2013 (4.4, 10th). However, you could argue some of that success is due to having Colin Kaepernick taking off from time to time, as San Francisco came in 19th in the league in 2011 (4.1 yards per attempt) with Alex Smith at quarterback.

Still, running the ball behind a massive front is what this team is built on, and what has made them so successful recently.

2) Can't ignore a possible two-headed monster at running back

Taking nothing away from Kendall Hunter or (for a brief period) LaMichael James, the 49ers may have never had a combination of ball carriers like they will in 2014.

While Frank Gore is entering the twilight of a borderline Hall of Fame career, he still should have enough left in the tank to be in the upper tier of backs in the league. However, the 49ers will have to do a better job of limiting his touches so he doesn't approach upwords of 280 carries like he did last year.

Enter rookie Carlos Hyde, who appears to have the makings of a feature back. Hyde was widely regarded as a steal when the 49ers selected him in the second round of the draft, and has looked the part so far this preseason. Hyde is averaging nearly 5.9 yards a rush with 88 yards on 15 carries through three games.

On average, the 49ers' second running back carries the ball about seven times a game under Jim Harbaugh. While it won't be a complete time share with Gore, look for that average to go up as long as Hyde continues to show he's a future star in the league. The tandem will be too good to not be the feature of their offensive attack.

3) They've tried this before

Truth be told, the 49ers have tried to be a passing team, it just didn't work. It started out fine, as Kaepernick lit up the Green Bay Packers to the tune of 412 yards and three touchdowns on 39 attempts in Week 1 of 2013. Those numbers could be a little misleading though, as the team still attempted 27 (non-Kaepernick) rushes.

It was in the following weeks that the Niners abandoned the run, as they only handed the ball off 27 times total in Weeks 2 and 3. Kaepernick attempted 55 passes combined in those games and was sacked six times. His numbers were putrid, completing only 47 percent of his throws for 277 yards. He didn't throw a touchdown pass and was picked off four times. The result was back-to-back losses by a combined score of 56-10.

In the end, San Francisco found success by reverting back to their bread and butter, the rushing attack. They reeled off five straight wins after the mini losing streak, handing the ball off an average of 33 times a game.

4) Kaepernick still has limitations

While he improved significantly over the second half of last season, Kaepernick hasn't shown in the past that he can be the type of quarterback who can sit in the pocket, scan the field and hit his fourth option if need be. In fact, he seems to bail out of the pocket if his first or second read is not there.

From Weeks 2-10 in 2013, Kaepernick only completed 53.7 percent of his throws and averaged 154 yards passing a game. Granted, he was without Crabtree and lacked weapons beyond Boldin and Davis, which was difficult for a developing young quarterback.

Kaepernick did turn his season around though, as his completion percentage jumped to 61.8 percent over the final six games of the regular season. He threw 10 touchdown passes (1.6 per game) to only one interception during that stretch, and his passing yards per contest jumped to 232.

While those numbers are excellent and show proof of an effective quarterback, they're hardly prolific. Even if Kaepernick averaged 232 yards and 1.6 touchdown passes over a 16 game season, his totals would end up being 3,712 and 26. While good, it would have put him in the middle of the pack in the NFL in 2013, at 15th and 10th overall respectively.

Kaepernick certainly has the ability and talent around him to eventually grow into a prolific passer, but he's not there yet.

5) Running is in Harbaugh's nature

Despite their possible intentions, you get the feeling that Harbaugh won't stray from the approach that has been his bread and butter his entire coaching career. The 49ers have attempted 1,304 passes since Harbaugh took over in 2011, which is the fewest in the NFL during that stretch. In contrast, the have attempted 1,495 rushes.

Harbaugh is a Bo Schembechler disciple who will stick to his roots. Barring a major jump in accuracy and reading defenses from Kaepernick, the team will most likely stay true to what Harbaugh believes. After all, this is a coach who had Andrew Luck while at Stanford, and still based his offense around the run. If Luck couldn't get him to alter his approach, it's possible nothing will.