Tom Brady channelled Mark Twain on Sunday night when he told reporters, "Reports of my death have been greatly exaggerated." 

Brady's New England Patriots had just demolished a previously undefeated Cincinnati Bengals team by a 43-17 score. With his strong individual performance (292 passing yards, 2 touchdown passes) keying a decisive win over a challenging opponent, Brady had answered the critics who'd believed his figurative death, as a football player (not to mention the Patriots', as a powerhouse team) was a distinct possibility.

With Sunday night's thrashing of the Bengals, Brady and the Patriots demonstrated why--in most team settings--there's a benefit to drawing a line between short-term feedback and overall performance evaluations.

This was a topic I'd recently discussed with Ethan Bernstein, an assistant professor of business administration in the organizational behavior unit at Harvard Business School. Bernstein cites the ability of legendary soccer coach Sir Alex Ferguson to draw this line between feedback and evaluation. Ferguson, the former manager of Manchester United, championed the use of vests fitted with GPS sensors on his players during practice. The sensors, Bernstein writes in the Harvard Business Review, allowed Ferguson to analyze his players' practice tendencies.

Yet in spite of his access to this data, Ferguson said he would "never criticize a player during a training session. That's where they try the irreverent things that will, and won't, work during a match."

To be sure, part of Ferguson's point is one legendary basketball player Allen Iverson made famous: Don't evaluate practice as if it's a game. But there's another piece of it, which all leaders and managers should understand: Even if you have the data with which to give feedback, you should still use discretion about how and when to deliver that feedback in the form of a performance evaluation.

Think about it: If Ferguson stopped each practice to critique his players for every single act of inefficiency, they'd probably stop experimenting. They'd also probably stop having fun. So would your employees, if they felt like every public minute of their day were a data point for a future managerial evaluation.

"There are all these breadcrumbs we leave digitally around the work place these days," Bernstein told me. "Collecting them can seem like a good goal, toward making the workplace meritocratic. But it may be hurting productivity. No one wants to feel constantly measured and evaluated."

And as Brady demonstrated last night, there's one other peril to constantly measuring and evaluating employee performances: You might turn out to be wrong.