Deans typically lack detailed technical knowledge to evaluate candidates (not to mention time), they just go with the flow, and want to run the department smoot

Deans typically lack detailed technical knowledge to evaluate candidates (not to mention time), they just go with the flow, and want to run the department smoothly. I think the real mechanism is this: those who make the decision (those with the most power, i.e. those who bring in the most funding and can threaten to leave if they don't get their way) already know whom they want and they cherry-pick data, eg "impact" figures, to bolster their case. That enables the dean then to justify the decision in public with those cherry-picked figures ... (the dean can hardly say we are hiring X because otherwise top funding getter Y will leave) I think Twitter is less important in STEM subjects than in social sciences or humanities, as STEM has more clearcut results.