ST. LOUIS (AP) -- Not long after rookie Zac Stacy made the St. Louis Rams' lineup, the running back became an indispensable part of the offense.
The fifth-round pick regularly gets 20-plus touches on game day, followed by rest early in the practice week to help preserve him for another game.
The bye week helped Stacy hit the field right away instead of taking mental reps for Sunday's game against the Bears.
''It's always good to get a break,'' Stacy said. ''I feel well-rested, ready to go. Ready to get back to work.''
During the four-day hiatus, Stacy watched alma mater Vanderbilt become bowl eligible for the third straight season. The school's career leading rusher connected with former teammates, too.
But he never really disconnected from the playbook.
''When you hear it so much, and we've been hearing some of the stuff as far as play-calling for the past 14 weeks, it's instilled in your mind,'' Stacy said. ''I was thinking about plays during the break. Absolutely. It's second nature.''
Coach Jeff Fisher has leaned on big-body backs in the past, Eddie George in Tennessee and Steven Jackson in St. Louis last season.
The 5-foot-8, 214-pound Stacy is a bit undersized for that type of duty, but has a bowling ball physique that makes him tough to take down, plus he hits the holes decisively.
''He knows his stuff,'' quarterback Kellen Clemens said. ''He's got that Vandy education and he doesn't take any negative runs, either.''
The Rams (4-6) traded away their last two picks of the draft to get Stacy, who is second among NFL rookies with 537 yards rushing and averaging 4.2 yards per carry with three touchdowns. He also has 15 receptions with a 6.5-yard average and one score.
This week, he'll be facing the 31st-ranked defense against the run. The Bears are allowing 133.9 yards per game.
''Everybody is trying to make everybody else one-dimensional and it's easier said than done,'' Bears coach Marc Trestman said.
Clemens appreciates the fact Stacy doesn't dance around and try to make something out of nothing and risk a big loss if the defense is stacked against the play.
''So, he gets back to the line of scrimmage, gets us a couple and we're able to be in second-and-8 vs. second-and-13,'' Clemens said.
The past four games, Stacy has two 100-yard games and four touchdowns. The past three, he's averaged 26 carries.
''Every week, every team is going to have great backs and good running games, and excellent schemes and things like that,'' Bears defensive coordinator Mel Tucker said. ''We just have to do our jobs.
''Nothing's really changed.''
Stacy totaled 28 touches in a surprising 38-8 rout at Indianapolis before the bye. He had 33 touches against Tennessee, 27 against Seattle, 21 at Carolina and 20 at Houston.
''I didn't really know how much it would affect me,'' Stacy said. ''Over 25 carries in this league, it's a lot and obviously you get sore and whatnot.
''The main thing is taking care of your body.''
Jackson had eight consecutive 1,000-yard seasons before leaving to take a free-agent deal in Atlanta after 2012. Stacy has a shot at giving the Rams another 1,000-yard man, stepping in after Daryl Richardson was sidelined with a foot injury.
''Jack's a big man, he's a real big man,'' Stacy said. ''Unfortunately, I wasn't able to meet him before he left, but I've heard some great things about Jack.
''I'd love to meet him but obviously it'll have to come in the offseason.''
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