"mediocre" is a bit harsh.
Perhaps a more balanced assessment might be that HB:
(1) did what he is quite good at very well, such as recognizing Pona's significant potential and walking away from (what we have to assume to be) partnership offers that, while big in absolute terms, under-priced the compound; but
(2) stumbled when faced with new tasks for the first time, such as managing the reporting and disclosure of SAEs in the PACE trial, the resulting affects on the label, the media fall-out, and PR regarding the roll-out.
<outrageous counter-factual thought experiment>
Does that mean that ARIA would jump if HB announced his retirement?
IMO, we would get a jump, but not for that reason -- the jump would come from the much better chance of a take-over.
</off-the-wall tangent>