Reasons to believe in Sam Bradford's big preseason

New Philadelphia Eagles starting quarterback Sam Bradford put up some impressive numbers in the Eagles' preseason win over the Packers on Saturday, completing all 10 of his passes for 121 yards and three touchdowns.

We don't yet have grades of his performance — we'll update those on the website once we do — but what our data of past seasons can tell us is this: If Bradford is able to stay healthy this season, he could have a good year as the Eagles' starting QB.

For one, Bradford quietly earned a positive grade from us in each of the 2012 and 2013 seasons. His PFF rating entering the season is 70.6, which ranks No. 23 in the NFL, just behind Colin Kaepernick and Jay Cutler. Eagles fans may not be too excited about that company for Bradford, but what it does say is that based on how he has played in the league to this point, he is in the range of other league-average passers.

The reason why that is encouraging is because most of the excitement over Bradford is tied up in the potential of what he can do for Philadelphia — both based on whether he can stay healthy, and how much better he'll be playing in Chip Kelly's offense.

We've seen what the latter has meant for QBs in the form of Nick Foles' 2013 season, during which he ranked No. 1 in PFF's QB rating, No. 5 in accuracy when under pressure, No. 6 in overall accuracy percentage and No. 7 in deep-ball accuracy. Some of those numbers were a little inflated — in our grading system, Foles ranked just 17th in the league in 2013 — but it does go to show the potential for a previously average NFL quarterback to perform very well for Kelly's Philadelphia offense.

Moreover, the key trait that presented itself more than once in those stats is accuracy, and as colleague Nathan Jahnke noted previously, that's an area in which Bradford has stood out during his injury-limited career.

None of this evidence provides the same confidence level that, say, Aaron Rodgers' PFF grades over the last five years would. Nobody is doubting that Rodgers should have another outstanding season in 2015, whereas we are left projecting with Bradford based on his limited play to this point in his career, while also taking into account his considerable injury history and whether he'll even be able to stay healthy for a full season.

But Eagles fans can feel good about two key factors: 1.) When he has been on the field, Bradford has been a slightly above-average NFL quarterback. 2.) In Kelly's offense, that could translate into a really good year.