The backlog has no bearing on future draws as since 2016 targets have already been met and we're now drawing from 2017 targets.
The reason as to why we're still seeing low ITAs is because targets are for actual PR landings, which have vastly exceeded targets this year (target 58k, landings 52k by June with 6 months yet to go). If ITAs settle above 1000 in October, scores can reasonably be expected to hit at least 481, but the only way that ITAs will go up significantly is if an internal decision is made to increase the 2017 target beyond 60k for FSW+CEC+FST. It's impossible to speculate on this.