No doubt the NFL schedule-makers thought Monday night's matchup of the Falcons and 49ers would be a clash of NFC titans.The teams battled for the conference championship last January, and Atlanta and San Francisco entered the 2013 season among the Super Bowl favorites.PHOTOS: Candlestick MemoriesUnfortunately for the Falcons and their fans, not much has gone right this season. Though quarterback Matt Ryan continues to be one of the best in the league, Atlanta has slumped to 4-10, and the Falcons have been horrible on defense. Atlanta ranks 29th in the league in total defense, allowing 386.3 yards per game, and give up an average of almost 28 points per game.As the teams head into their Monday night matchup in the last regular-season game ever at Candlestick Park – and most likely the last NFL game ever at the stadium – the Falcons appear vulnerable to a 49ers team that seems to be peaking at the right time.The Niners have won four straight to get to 10-4 and are in position to clinch a playoff spot this weekend. And, since the return of wide receiver Michael Crabtree, quarterback Colin Kaepernick and the passing game have been clicking. The 49ers are 3-0 with Crabtree...