Why does having a higher line mean more 'risk'? I'd say the opposite and sitting deeper, inviting pressure, reactive defending, ceding possession, dropping deep when the opposition attacks is not conductive to a 'good' system that wants to stop leaking goals. We talk about individual mistakes and it's not Ole's fault that the performances of players are poor in games but it's a systematic failing also.
We play defensive and yet free-for-all football because our natural tendency is play a deeper line to accomendate for the fact we are shite at creating chances through possession so we hope for individual sparks or chances in transition i.e counter attacks. This is not sustainable or giving the defensive and offensive players the best platform. It's arguably the best foundation we've had post-Fergie and Ole deserves credit for that but we need to continue to improve.
There's much to be said about Bailly's game or Lindelof's for that matter. Let's see how the former performs with a consistent set of games. With Lindelof's injury, it could be our only choice anyways.