Of the many mystifying choices that should result in Pat Shurmur’s dismissal a month from now, this one has escaped notice: the Browns are overusing their workhorse running back.

That’s right, Trent Richardson is carrying too much of the load. This diminishes his effectiveness and carries real risks for the longevity of this franchise skill player. Remember, he’s a rookie who missed the preseason with arthroscopic knee surgery and has battled bruised ribs during the season.

Yet, through 12 games, he has 73.5% of the team’s rushing attempts (including QB scrambles and end arounds). That’s easily the highest share of the ground-game workload in Browns history, with one exception.

In 2005, Reuben Droughns came to town, and Romeo Crennel rode him roughshod. Droughns carried 309 times, an astounding 78.2% of the team’s total attempts. The hard-charging runner was never the same after that.

Jim Brown, as tough a workhorse as nature ever designed, never had even 65% of the team’s total carries.

Stories abound throughout the league of overworked runners soon losing their mojo and falling prey to injury. Compare the Jamal Lewis of 2007 (298 carries, 4.4 average) and 2008 (279, 3.6). Read up on Jamal Anderson and Terrell Davis, for example.

Factor in Richardson’s team-leading 44 receptions (Droughns had 39 in 16 games), and the point is obvious. Less is more. Building the Browns is a marathon, not a sprint.

It’s not as if they lack backfield depth. Montario Hardesty is running well. Chris Ogbonnaya is a decent player. Brandon Jackson can’t even make the 45-man game day roster, and he led the Super Bowl champion Packers in rushing just two years ago. Josh Cribbs is itching for opportunities, and his career rushing average is 5.8 yards per carry.

No doubt Trent is a special player, but most accounts portray his rookie year as something of a disappointment. The injuries are part of that, but the way he’s overused is a problem too, one that may have serious implications for his career.