Dan Marino (the closest QB to Manning) had a season where he threw 16 TD's once and passed for just under 3800 yards, there was no reason for that but it happened, before then he had never thrown for less than 20 when playing a full season. Manny Sanders has exactly one season with more than 2 TD's, Latimer has never played in the NFL. Neither of them at this point are actual replacements for a guy who had 1288 yards and 11 TD's (Sanders total for his entire career). Welker tore his ACL it happened at the end of the season so he didn't miss any games but it still happened, he also battled concussions last year.