As Steel alluded to, its history that has me concerned about Eli, and this from a huge Giants fan. Whether it is Eli himself, the team, the team's strategy, the weather/wind or a combo of the above, there is a pattern of weak finished after very strong first halves of a season.
If it were not for this, I would go Eli - he's looked great from a fantasy perspective, wins games from a football perspective and has better weapons than Pitt. However, history makes this more equal for me, possibly leaning to Roeths from a fantasy perspective at least.