Spiller's benefit is obvious. With Jackson and Lynch sidelined, Spiller is in line to get the bulk of the carries and be the feature back should Lynch and Jackson's injuries hold them out into week one of the regular season.
But Simpson's benefit might be the one that flies under the radar more.
Simpson is currently scrapping for a roster spot, and this should only help his cause, for multiple reasons.
First and foremost, he could provide depth at the running back position, which is important especially with a rookie in line to see most of the carries. Simpson might wind up being the No. 2 back for a week or two if Lynch and Jackson miss serious time, unless Buffalo brings in a veteran for insurance.
But Simpson would also help in the return game.
Spiller is an explosive return man, and by all means should be the leading candidate to be both the kick and punt returner if the Bills have a healthy backfield.
However, if Spiller is starting and getting a lot of touches, there is a good chance the coaching staff will not want to ask their feature back to also be their return man in order to keep him fresh and lessen the risk of injury. In that case, Simpson would likely take over as the return man after looking very good on returns in the preseason game against the Redskins.
While I'm sure everyone (including me) certainly hopes that Lynch and Jackson can make speedy recoveries, their injuries might be a blessing in disguise for someone like Spiller, looking to get more touches, or Simpson, who is just fighting to make a team.