People aren't generally able to keep up the discipline to time when to pass on tickets to hide changes in their ability, unless it's forced by a constant anxiety.

Developers are also not very good at estimating how long something is supposed to take. If there was even a 10% jump in profitability in the software department it would have been obvious to bean counters and managers. You'd also see a massive recruitment spree, because large organisations ramp up activities that make money in the short term.