Picks being traded are -
To Buffalo: PHI 1st (5th overall)
To Philly: BUF 1st (9th overall), BUF 3rd (74th overall)

Draft pick trades this early in the 1st rd never happen, I know... but what if

I think from a Sabres POV this is a steep but fair price to pay to move up from 9 to 5. I would consider doing this from Buffalo if Wright-Slafkovsky-Cooley go 1-2-3, and Seattle takes one of Jiricek or Nemec at 4. I'd take the other at 5.

Flyers save money off the cap for their rebuild moving the Atkinson contract and pick up an early 3rd this year for moving down from 5 to 9

This is a terrible trade for Philly. Atkinson was one of the bright spots for them last season and is worth a fair bit on his own. Pekar is a C level prospect who may not be in North America much longer if he doesn't show something. Also with the Flyers hiring Tortorella they are not rebuilding, they are going to likely retool a bit and try to compete. Atkinson had his best seasons under Torts, which just makes it even more unlikely they even consider trading him.