There are two legitimate candidates for this award, the way I see it: LB Tamba Hali and CB Brandon Flowers.
Guys like LB Derrick Johnson and DE Glenn Dorsey have played very well but not at the level of Hali and Flowers.
For my defensive MVP through the first quarter of the season I'm going with Hali over Flowers.
Hali leads the team in sacks (4.5) and fumbles (2) and has been far and away the most consistent force rushing the passer. The Chiefs pass rush this year isn't considered the NFL's worst like it has been the last couple of years and that's mainly due to Hali.
He's entering a breakout season right (also a contract year) and on pace for 18 sacks.
His affect on the team has been incredible and that's why he's my defensive MVP through the first quarter of the season.