You may be wondering why the Buffalo Bills signed Matt Leinart and traded for Thaddeus Lewis on Sunday in an effort to bolster their suddenly-thin quarterback depth chart. Tim Graham of The Buffalo News, citing a source, provides clarity: the Bills are seriously concerned about the health of Kevin Kolb.

Source tells me Bills concerned Kevin Kolb's concussion may be career-ending and they're proceeding with that in mind. — Tim Graham (@ByTimGraham) August 25, 2013

Kolb was removed from Saturday's 30-7 loss to Washington with what was described as "concussion-like symptoms." That's of particular concern for him, as he also lost part of the 2010 season to a concussion as a member of the Philadelphia Eagles, then part of the 2011 season after his trade to the Arizona Cardinals.

The Bills signed Kolb as a free agent in March to compete for the starting job; he spent most of the spring and summer months even with rookie EJ Manuel on the depth chart. Now, as the Bills cross their fingers that Manuel is healthy enough to play in Week 1 and scramble to fill out their depth chart, Kolb's career is seemingly in jeopardy. Please keep the man in your thoughts.

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