Because he is the #3 WR for a team on which the #1 WR is definitively the primary target, followed by the #2 WR, the TE, the FB/RB and finally the #3 WR. Thus far, at least, the Texans have rarely had a third WR on the field, instead running most of their plays out of the I-formation with a TE and two WRs. Their #1 priority (IMO) is to protect the QB and to run the ball to set up the pass -- they are not a spread offense. Of course, they've enjoyed the benefit of playing from ahead thus far, but even when down 14-0 against CAR they stuck to the same basic plan. Additionally Kubiak, despite Jones' stellar camp, is very high on Walter and I think he, more than Jones, is the guy who will get most of the looks (followed by Daniels) if AJ misses any significant playing time.