The easy part of the first week of free agency is assessing whether the Bears improved their roster. Based on the histories of tight end Martellus Bennett and left tackle Jermon Bushrod, the Bears improved dramatically from Kellen Davis/Matt Spaeth at the former position, and over Gabe Carimi/Jonathan Scott at the latter (J’Marcus Webb is going to right tackle so the real standard is whether the Bears upgraded at tackle generally -– they did.) The harder part is determining how much real good it did. That's because the true measure of the week is whether the Bears gained on their NFC North rivals and whether they advanced vis-a-vis their 2013 opponents. In some situations, the Bears gained significant ground on the opposition; in others, that remains to be seen. Detroit Lions Detroit lost elite defensive end Cliff Avril to the Seattle Seahawks, a major blow to the defense. They also saw veteran left tackle Jeff Backus retire. But the Lions used their first pick in the 2012 draft on Iowa tackle Riley Reiff, and Backus finished last season with a lower rating than Bushrod or Webb, according to Pro Football Focus grading. Reiff, however, in spot duty (336 snaps, largely as a short-yardage tight end) graded well in both run and pass blocking. At this point of Backus’ career, Reiff is an upgrade. The problem for the Lions is that highly regarded right tackle Gosder Cherilus, one of the top tackles on the market, departed to take care of Andrew Luck in the Indianapolis offense. Consider the Lions’ tackle transactions, at best, break-even.