Okay, here's what happened: at the beginning of the year, the pairings were slavin pesce, hanifin faulk, fleury tvr. standard nhl unit, top 4 vs top 9, fleury sheltered against the 4th line.
Fleury and dahlbeck are bad nhl players, no two ways about it. fleury was taken ahead of w nylander and n ehlers....just awful.
what ended up happening: because everyone on the 4th line unit sucked (cept tvr, who wad better than advertised), they got pinned a lot in their ozone. and a team rolling 4 lines could execute a switch and get crosby or ovie or stamkos out against a tired hadyn Fleury, nordstrom, kruger and jooris. and score.
at forward, jordan staal and whomever were good defensively, but skinner and derej ryan were trainwrecks in their dzone. skinner and ryan were put together and heavily sheltered with ozone starts, also because skinner is a guy you want for an offensive zone faceoff.
to fix the defense problem, peters started putting pesce slavin out with the 4th line and then keep that d pair out against the 1st line. since you now have basically a 3, two 4/5's and two 6's at best against the 2nd and 3rd lines, peters split up hanifin and faulk(best two defenders), put fleury with faulk so Faulk could babysit the 6 and tvr with hanifin. peters put rask and (generally) the responsible wingers with faulk and fleury/dahlbeck because putting fleury with skinner and ryan would be a disaster. so hanifin/tvr goes with skinner/ryan and the ozone starts.
the funky deployment/ advanced stats is the result of having three different groups (fleury, skin/ryan, 4th line) that needed to be sheltered from nhl comp. you get something like fleury having harder usage than hanifin, but if the canes were holding onto a lead fleuey's minutes were cut and hanifin placed with faulk.
tl:dr: peters calculated he'd rather have fleury/ dahlbeck with rask, faulk and mcginn in the dzone than fleury with skinner and ryan in the ozone.