With Portis injured, Denver finds a replacement -- again

Four backs have topped 1,000 yards rushing in eight of the last nine years.
DENVER (AP) -- With his top running back ailing, Denver Broncos coach Mike Shanahan did what he always does: plug in a capable replacement.
Clinton Portis, a two-time 1,500-yard rusher, was hobbled by a sprained ankle when the Broncos played the Indianapolis Colts on Sunday night. So Shanahan turned to rookie Quentin Griffin.
Griffin steps up
Griffin, who had rushed for only 135 yards all season, ended up with 136 yards on 28 carries and turned a screen pass into a 24-yard gain to set up a touchdown as Denver beat the Colts 31-17 to earn a wild-card playoff spot.
Sharing playing time with Mike Anderson, who ran for 56 yards, Griffin proved to be exceptionally quick on Indianapolis' artificial turf.
"The guys up front were doing the job, and all week long the guys pumped me up," he said. "Clinton, especially, kept telling me what to look for. I feel real good in this system."
Doesn't everybody?
Griffin could be the latest in a line of standout Broncos running backs, seemingly interchangeable parts in a nearly unstoppable ground game. Four Denver backs have topped 1,000 yards in eight of the last nine seasons.
Davis started it all
Terrell Davis was the NFL's top running back in the late 1990s, winning the MVP award when he rushed for 2,008 yards in 1998. He helped lead the Broncos to two Super Bowl victories before blowing out his right knee.
Enter Olandis Gary, who subbed for Davis as a rookie in 1999 and ran for 1,159 yards. Then, with Davis and Gary both injured in 2000, Anderson bolted for 1,487 yards to capture the NFL's Offensive Rookie of the Year award.
Then came Portis, who ran for 1,508 yards in earning the league's offensive rookie honor in 2002. This year, Portis ran for 1,591 yards in the first 14 games -- second-best in the NFL -- before getting injured against Cleveland on Dec. 14.
Is the success due to shrewd personnel decisions or the scheme?
"Any time you have a good running game, it's a combination of a lot of things, not just a great running back," Shanahan said. "We have some excellent running backs, and (assistant coach) Bobby Turner does a great job with them.
"I think our offensive line has done a great job of giving the running backs opportunities, and the wide receivers take a lot of pride blocking for the backs."
O-line gets credit
Quarterback Jake Plummer said it all derives from the offensive line.
"Those guys up front are awesome," he said. "It starts with (center) Tommy Nalen in the middle and goes all the way across the board."
Plummer insisted "you can't just plug in any running back. Our guys have to be able to read keys on blocks and fronts, where guys are stunting and know where those holes are at. I think we have the caliber of backs that once the line gets them 5 or 6 yards, it's up to them to get more."
Griffin wasn't exactly an unknown coming out of college, but there were questions about how effective he might be in the NFL.
A durable and explosive runner at Oklahoma, Griffin ran for 3,756 yards and 44 touchdowns, including a school-record 1,884 yards last season. But he wasn't drafted until the fourth round, primarily because of his size -- 5-foot-7 and 195 pounds.
Broke leg in camp
The Broncos counted on Griffin being Portis' backup this season, or at least being a third-down specialist because of his ability to catch the ball. But he got a late start after breaking his leg on the first day of training camp.
Finally, he seems to be catching up.
Anderson told Griffin the Indianapolis game could be his coming-out party.
"All week long I told him, 'It's your time, man,"' Anderson said. "He came through big time for us. I'm so proud of him."
Plummer said Griffin "was unbelievable. You give him space and he's got those swivel hips and he makes guys miss."
Denver wide receiver Rod Smith recalled his first memory of Griffin.
"He broke his leg in camp and he was all nervous," Smith said. "He was running around saying, 'They're going to cut me.' But he has battled back and done some great things for us in practice, and all of a sudden you call his number and he goes out and has a 100-yard game. I'm not surprised a bit."