This is pure speculation, which is why actual data would be useful. Is a measured 0.4x performer that way for innate reasons or is that something which some combination of training and mentoring, better tools, streamlined environments, etc. can help with? — or is the way that's measured even valid? I've seen a few cases where someone got flack for being slow until wider perspective showed that they were the only one solving the customer's real problem because it turned out that what they were doing was more complicated than it looked and/or the other guys were “solving” it in ways that required lots of ongoing maintenance.