Willis McGahee has long been a reliable fantasy performer. But don't make the mistake of looking at his past performance as an indicator of future results.

In fact, McGahee would be a bad pick to start this week. Here's why.

McGahee is coming off a rib injury. He is probable, but not at 100 percent. The first time he takes a hit, it's going to hurt a bit more than usual. That might make him a bit more hesitant than usual. It's understandable, but it's not going to help your fantasy team.

Additionally, McGahee just has not had a great year. He has 213 yards on 50 carries, good for a 4.3 yards-per-carry average. Not terrible, but there are better options out there. 

With Peyton Manning now on board, this is a passing team. The Broncos have accumulated some nice weapons, led by Demaryius Thomas and Eric Decker. This is not the option-based, Tim Tebow offense anymore. It's a pass-first, pass-second, pass-third offense.

Despite their game against the Dolphins and Reggie Bush—which might have been an anomaly—the Raiders, the Broncos' Week 4 opponent, have a pretty solid run defense. They held Issac Redman to 27 yards on nine carries. They also held the Chargers to only 32 yards rushing, spread out across five players. 

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McGahee is also pretty up and down. He had a nice performance against the Falcons, with two touchdowns and 113 rushing yards. But he's had two clunkers as well. It's hard to trust him to give you a reliable performance. 

Between the injury, the nature of the Broncos offense, the underrated performance of Raiders run defense and his unpredictable nature, McGahee is a pretty bad fantasy option this week.