Need some flex help for my footclan title

Current lineup - half ppr

QB Brees
RB Leveon Bell
WR Thielen
TE Gronk
FLEX Fitzgerald
FLEX Ertz (huge question mark - risk of being sat)
FLEX Freeman
K Lutz
DST Jags

My bench:

Westbrook
Cooper
Olsen
Wallace
Martavis Bryant

I think the only help I need is do I start Ertz? My gut says put in Wallace, but Ertz has been a great flex for me, pretty much all season.

HELP FOOTCLAN!