I've just completed my first year with a Dynasty IDP/PPR League and I've come to the realization that it can be as CRAZY as you want to allow it to become. Just know that "BPA" is a relative term. If your starting roster is inclusive of "Defensive Backs," you don't necessarily want a "Shut Down" corner on your roster, because the ball is never thrown his direction, so he get's no points. The Safety position appears to me to be more valuable than a Corner Back, because the Safety tends to be a "Ball Hawk" and is involved with more stats. With ALL this being said, depending on the number of rounds of your "Rookie" draft, although Defensive Backs generally score more points in this NFL's current "pass happy" league, I wouldn't recommend drafting the "best one." More than likely, I wouldn't draft one at all, because a "190-210 point" Defensive Back is a dime for THREE dozen. Pay attention to the waiver wire and you'll always be able to pick one up on the cheap
Defensive Ends are ALWAYS involved in more stats than Defensive Tackles. More often than not, Defensive Tackles are strictly put there to tie up more than one blocker at a time. Other than the elite, they don't pursue the play. But beware of the defensive coordinator's scheme, because an AWESOME Defensive End can easily be re-defined into a good Outside Linebacker (see Mario Williams, DeMarcus Ware). As Defensive Ends, they'd be racking up major points for their position, but if they're labeled as "Line Backers" in your league, they're more than likely barely decent
For all it's worth, my recommendation would be to rank your best players by position. In a PPR league, Running Backs that are sure to be part of the passing game are GOLDEN (see MJD, Matt Forte, Roy Helu). Petersen and Turner are great, but you're going to be primarily dependent upon touchdowns, and as those drop, so go the points (also see Blount, Igram)
Receivers and Line Backers are where I'd put your second level of weight. Justin Blackmon and Michael Floyd should more than likely be among the top five selections, EASY. Primarily because of the targets they should receive on whichever team they go. When looking at Receivers, you want those that are targeted a lot. It seems to me, "Wide Outs" are no where near as valuable as those receivers in the "Slot." Although Mike Wallace was great, in our league Antonio Brown averaged less than 2pts a game less and was had for basically nothing. And Brown didn't become a starter until mid-way through the season. Wes Welker was the 2nd best receiver with only 9 touchdowns. Look for potential targets when evaluating a receiver. And as far as linebackers go...? You want those that are predicted to MIDDLE LINEBACKER. Go for those that pursue EVERY play. London Fletcher is a stud! Regardless of size, Luke Kuechly should be a solid selection and be a future Brian Urlacher or John Lauranitis
With the exception of your TOP tier (Cam Newton 2011 and Luck/Griffin 2012), Quarterbacks should make up your fourth tier. I wouldn't expect Tannehill to be picked until at least the top 6-8 Running Backs/Wide Recievers are selected. And even though Line Backers appear to be weak this year, I can see 4-6 being drafted prior to the third Quarterback. So Ryan will more than likely be taken off the board around selection 24 (depending on the team that selects him and the probability of him starting right off the bat).
Let me continue with don't ignore Defensive Ends and Tight Ends in this draft. Before the year started, I expressed how it seemed too many teams were ignoring the Tight End and filling it in late. Players like Gronkowsky, Graham, and Hernandez are proving the point that more teams seem to be leaning towards utilizing the short pass to the Tight End in lieu of a stale running game. Remember, Marcus Colston was originally drafted as a Tight End by New Orleans. Defensive Ends are a whole new breed. Tell me who wouldn't love to have a non-stop pursuit machine like Jason Pierre-Paul or Jared Allen. Keep an eye on Coples, Perry, Branch and Mercilus. Tall, athletic, and solid on pursuit. Depending on the team that selects him, getting Coples anywhere from 10-16 in an IDP/PPR league should prove to be a solid move.
Finally, don't worry about kickers. They're not even worth reviewing. I hope this toilet material was worth a read and provides some valuable advice. At least I can guarantee it's worth the price. PEACE!