Well, lets review.
McNallys years with Giants
1st year: Tiki only started 1 game.
2nd year: Tiki started 12 games, averaging 4.7 YPC
3rd year: Tiki started 9 games, averaging 5.2 YPC
4th year: Tiki started 15 games, averaging 4.6 YPC
5th year: Tiki started all 16, averaging 4.4 YPC
Thats 53 out of a possible 80 games ... yet he still averaged 4.7 YPC. Not really bad IMO.
More time for Eli to throw? In 2004, the Giants were tied for 2nd in sacks allowed with 52 sacks. in 2005, they were ranked 3rd in sacks allowed with 53 sacks. The last year McNally was there they had 44 sacks. 8-9 sacks fewer.