Buffalo Bills preview (No. 21): Rex Ryan has plenty of talent, but what about QB?

Key arrivals: LeSean McCoy (running back), Charles Clay (tight end), Percy Harvin (wide receiver), Tyrod Taylor (quarterback), John Conner (fullback), Alex Carrington (defensive end)

Key departures: Scott Chandler (tight end), Kiko Alonso (linebacker), C.J. Spiller (running back), Lee Smith (tight end), Chris Hairston (offensive tackle), Da'Norris Searcy (safety)

2015 Schedule:

Sept. 13: Indianapolis, 1 p.m.

Sept. 20: New England, 1 p.m.

Sept. 27: at Miami, 4:25 p.m.

Oct. 4: New York, 1 p.m.

Oct. 11: at Tennessee, 1 p.m.

Oct. 18: Cincinnati, 1 p.m.

Oct. 25: at Jacksonville, 9:30 a.m.

Nov. 1: BYE

Nov. 8: Miami, 1 p.m.

Nov. 23: at New England, 8:30 p.m.

Nov. 29: at Kansas City, 1 p.m.

Dec. 6: Houston, 1 p.m.

Dec. 13: at Philadelphia, 1 p.m.

Dec. 20: at Washington, 1 p.m.

Dec. 27: Dallas, 1 p.m.

Jan. 3: New York Jets, 1 p.m.

TRAINING CAMP QUESTION: Can the Bills avoid having the NFL's worst starting quarterback situation?

IF EVERYTHING GOES RIGHT

Ryan and offensive coordinator Greg Roman's plan is executed to perfection and the Bills have a stifling running game mixed with an efficient passing attack. The defense certainly should be one of the very best in the league. One prominent scout told FOXSports.com that if the Bills win less than 10 games, it will be widely considered a failure.

IF EVERYTHING GOES WRONG

BREAKOUT PLAYER: Wide receiver Sammy Watkins

Watkins faded during the second half of his rookie season and suffered a hip injury that required offseason surgery. Although uncertainty remains at quarterback, the Bills signed some high-end skill-position talent this offseason to complement Watkins as he tries to prove worthy of being the first wide receiver drafted last year, ahead of Odell Beckham Jr.

CIRCLE THE DATE GAME: vs. New England in Week 2 (1 p.m. ET/Sept. 20)

Even if Patriots quarterback Tom Brady remains suspended, defeating New England would be a huge step for a Bills squad that has won just two of the past 22 meetings (including Week 17 last year, when the Patriots rested their starters).

ALEX MARVEZ'S PREDICTION: 8-8, fourth place

You know the expression that insanity is when you keep doing the same things over and over again and expect different results? This applies to  Ryan. After ineffective quarterbacking torpedoed his tenure with the New York Jets, one would think Ryan would have made addressing the position his top priority after arriving in Buffalo.

Instead, the Bills enter training camp without a clear-cut starter or even backup. Ryan must hope that: A) Cassel regains his 27-touchdown, seven-interception form from the 2010 season; B) Taylor was a hidden gem sitting as Joe Flacco's backup the past four years in Baltimore; or C) Manuel's NFL career can be salvaged.

Whoever wins the job will have a strong supporting cast led by McCoy, tight end Charles Clay and wide receivers Percy Harvin, Sammy Watkins and Robert Woods. Plus, the Bills don't need the next Jim Kelly under center to win. A game manager who avoids excessive turnovers should be sufficient considering the monster of a defense Ryan is preparing to field. Every member of the front four that helped the Bills register an NFL-high 54 sacks in 2014 has returned.

As the offense finds its groove under Roman, Buffalo will need the defense to carry the team early in the season with a schedule that features opening games at home against Indianapolis and New England followed by a Week 3 road trip to Miami.