Trading always has this trade off in terms of (dumb and fast) vs (smart and slow). In the past few years, I think it's been more beneficial to be fast enough,

Trading always has this trade off in terms of (dumb and fast) vs (smart and slow). In the past few years, I think it's been more beneficial to be fast enough, but very smart. So, in this sense, technical ability only takes you so far since "smarts" come from domain expertise or, plainly, just creativity. Team composition matters, since your technical guy needs to be complemented. The objective, of course, is making your team take your organization towards the holy grail of (smart and fast). I'm not sure if this directly answers your question, but perhaps it describes the scenario in which technical ability isn't everything. I do not think assembling a team for HFT is easy at all, especially now. There are a lot of good reasons for being very peculiar and selective. I am not sure industry outsiders who are just applying understand the dynamic or, in many cases, why a seemingly great candidate is rejected.