Good read. Some of the highlights....
First Down Pass Defense- According to Football Outsiders' 2013 almanac (subscription required), the Patriots were the second-worst defense in the NFL on first down, despite having the sixth best run defense. Teams that threw early and often on the Pats' defense were successful, and it's why the Ravens lit the Patriots up through the air on first down in the AFC Championship.
Third Down Pass Defense- Football Outsiders' almanac had the Pats 19th in their DVOA metric on third down, and though they had their best third-down percentage since 2009 (40%), they were still ranked 20th in the NFL.
Again, it's the pass defense that needs help.
Stretching the Field- the offense lacked explosion, and with no receiver to challenge the defense deep and outside, teams began to crowd the short zones, and make the receivers pay for any catch.
Now, with the departures of Welker and Branch the passing game is in full transition, and with that comes the advantage of unpredictability, but the disadvantage of inconsistency. The Pats added multiple potential X-receivers with potential to stretch the field, including veteran Michael Jenkins, and rookies Aaron Dobson and Mark Harrison.
The Verdict- The Patriots brought in a number of players to compete at the spots where they were weakest at in 2012, but quantity doesn't always equal quality. New players will have to emerge, especially at the receiver and pass rusher spots.
If they do, the Patriots could be ready to take the final step toward raising the Lombardi Trophy once again.