When a NASCAR driver with as successful a career as Tony Stewart has had, his current 51-race losing streak is bound to invite its share of theories as to why.

Currently, Stewart is 30th in the Chase for the Cup points standings and has just one top-10 finish in 10 races so far this season.

Driving with reduced horsepower in Sprint Cup has Tony Stewart baffled?

Autoweek.com examined the struggles of the three-time Sprint Cup champion and reported that Stewart's multiple hats he wears in racing has taken its toll on him.

"Everyone in the garage has an opinion about Stewart's struggles," the Autoweek article began. "He's almost 44 and the grind, they say, has worn him down. He's distracted by ownership of two open-wheel sprint car series, spends too much time with the sprint car team he owns for Donny Schatz and is busy with the dirt tracks he owns in Ohio, Kentucky and Illinois."

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None other than the king, Richard Petty, echoed the sentiment of the energy drain of being a team owner and a driver.

"Anything that takes your attention away from driving your own car hurts," Petty told Autoweek. "Owning tracks and teams and keeping up with business stuff has stretched him too thin. I think he's distracted by things other than driving his race car."

Another issue related to his misfortunes the past two years - the broken leg he suffered in 2013 and the tragedy he suffered last season with his involvement in the death of dirt-track driver Kevin Ward Jr. - is the time away from the track that he had to take.

A former driver who had an injury-plagued career told Autoweek that Stewart's extended absence from the circuit affected his outlook on his racing career.

"I don't think Tony takes care of himself like he used to," the driver said on the condition of anonymity. "He isn't as mentally or physically ready to race. You know, you miss some races; you sit home; you watch someone else in your car; you get used to not being there. Sooner or later you think, 'Hey, I miss it, but the world didn't quit because I'm not racing. This isn't so bad.' Every driver who's had to sit out races loses some of the edge that made him great. I think we'll see that when (injured) Kyle Busch comes back."

Stewart said earlier this week that he still has not mastered driving cars with limited horsepower that came along with the NASCAR rules changes this year. Stewart-Hass Racing director of competition Greg Zipadelli echoed Stewart's sentiments to Autoweek.

Zipadelli "says the No. 14 team is behind because Stewart had barely a half-season in the new Gen 6 car before the Sprint Car injury in 2013. He didn't return until Speed Week of '14, a month after missing offseason testing. Since then, there have been rule changes and more aerodynamic adjustments, and Stewart is climbing a steep relearning curve," Autoweek reported.

Beyondtheflag.com, however, suggested that after 10 races this season, Stewart should have made the necessary adjustments.

"After a few races the new package can be an excuse but after 10 I'm not so sure," beyondtheflag.com reported.