The only answer I can come up with is that Lacy is the best all around RB they have, they like him in pass pro a lot more, and they felt like they'd eventually get opportunities to exploit the Lions secondary for explosive plays. M3 has been fond of referencing the count of explosive plays for vs against this year and it seems that thinking has surfaced in his public analysis lately, even though it's been apparent to Packers fans for 5 years.