MoM is decided after everything is over & done, so the adjudicators cannot say that at the end of the 35th over Pak seemed to be winning and that was due to Wahab’s spell, so lets give him the MoM award.
After the match has been decided, the contribution of the contenders to the overall result is seen and then the MoM is decided. If not for Sachin’s 85, India would have probably lost in the 40th over today.