Losing Steve Smith to a torn pectoral muscle certainly can't be seen as anything other than a negative for the Giants, but Big Blue is absolutely in good hands when it comes to his replacement, Mario Manningham.
Manningham has posted superb metrics this season. By my count, he has caught 35 of the 47 passes thrown his way and gained 476 yards. Throw in two defensive penalties for 10 yards and it means he has a completion/penalty rate of 75.5% and a yards per attempt (YPA) mark of 9.9. To put those into perspective, consider that there are normally only around 5-10 wide receivers in the NFL that will post numbers that high in both categories at season's end.
It isn't just overall production where Manningham excels. His vertical pass totals (vertical defined as aerials thrown 11 or more yards downfield) are tremendous. He has 13 receptions in 22 vertical attempts and has tallied 302 yards and three touchdowns. That equates to a 13.7 vertical YPA, which qualifies Manningham for near-elite status in that metric.
Losing him as a No. 3 wideout may leave the Giants weak at that position, but Manningham should be more than capable of replicating Smith's starting wideout production until he returns.