​The Detroit Lions have begun making moves in their secondary, signing cornerback Jalen Mills to the practice squad. After allowing 71 points over the last two games, Detroit’s secondary desperately needed some help.Now, Mills isn’t going to come in and turn this defense around, but he can’t possibly be any worse than what we’ve seen so far. Let’s break down the Lions’ secondary and examine just how bad their performance was using Pro Football Focus grades and statistics from their 31-41 loss to the Bills.Christian IzienIzien played in his first game of the season and had the best PFF grade among all Lions defensive backs, earning a 72.9 overall defensive grade and a 63.7 coverage grade, which was the second-highest among the group.Izien played just 26 snaps: 11 inside the box, six at free safety, four in the slot and five outside. He recorded two tackles.Chuck ClarkChuck Clark played 64 snaps and earned a 69.2 overall defensive grade, along with a 73.2 tackling grade and a 62.7 coverage grade.He recorded nine tackles, was targeted twice and allowed two receptions for 28 yards. Clark played 20 snaps inside the box, 40 at free safety and four outside.Avonte MaddoxAvonte Maddox had a poor performance, playing 27 snaps and earning a 27.4 defensive grade, a 79.9 tackling grade and a 27.6 coverage grade.Maddox allowed two receptions on two targets for 55 yards and a touchdown, resulting in a 158.3 passer rating when targeted.Unfortunately for Maddox, his day only got worse as he suffered a season-ending foot injury.Thomas HarperThomas Harper played 33 snaps, but his role will likely increase following Maddox’s injury.Harper earned a 43.8 defensive grade and a 48.7 coverage grade. He recorded just one tackle and was targeted four times, allowing three receptions for 30 yards and a touchdown. That resulted in a 135.4 passer rating when targeted.Harper primarily played free safety, accounting for 23 of his 33 snaps at the position.Khalil DorseyDespite the Lions ruling out Keith Abney and Ennis Rakestraw, we saw just two defensive snaps from Khalil Dorsey. He did manage to record one tackle.DJ ReedDJ Reed played 71 of the Lions’ 74 defensive snaps and earned a 61.4 overall defensive grade, along with a 61.3 tackling grade and a 68.0 coverage grade.Reed recorded one quarterback pressure and one quarterback hurry, along with five tackles and one missed tackle. He was targeted twice and allowed two receptions for 20 yards while also committing one penalty.Overall, Reed was the Lions’ best cornerback on the day. It seemed like the Bills were avoiding his side of the field and instead choosing to target Rock Ya-Sin.Roger McCrearyMcCreary played just 18 snaps, earning a 41.8 defensive grade and a 40.5 coverage grade.I will say I’m slightly surprised by the low grade because McCreary was targeted twice and did not allow a single reception. He allowed just a 39.6 passer rating when targeted but did commit one penalty.McCreary lined up in the sl