The fifth part of our 32-part series on Yahoo! SportsIn 2011, the Detroit Lions opened the season at 5-0, finished 10-6 and reached the playoffs for the first time since 1999.A year ago, Jim Schwartz's club won only four games all season.The Lions split their first eight contests and ended 2012 on an eight-game losing streak.So what can we expect in 2013?There is this to consider. Detroit was the only team in the division not to win at least 10 games last season. And Schwartz's club laid a goose egg when facing their divisional rivals a year ago (0-6).But hope springs eternal. And it is onto 2013 and here we will take a look at five players who could be critical to the team's success this upcoming season. While in some cases the obvious will be stated, in other instances the focus will be on a newcomer to the team or a performer looking to rebound from a disappointing year.