Picture this:
My first real coding job out of college, my first big project.  “Create a Direct Bill / Credit Memo entry system in the ERP.  Model it after the Order Entry system.”  Six weeks into the project, on a Tuesday at 11:13 a.m. I type a command to remove all the temp files that go down in IT history:

rm -rf * .tmp

Yeah, 54,144 lines of Progress4GL code wiped out.  Gone.  Forever.

But wait, what about your git repo?  This was pre-git and pre-svn.  In fact, we were using CVS (not the pharmacy), but since it was a huge pain, I wasn’t using anything.

Of course, I did the developer-walk-of-shame into my bosses office and admitted my error.  Head down, I held my breath… only to hear, “Oh, that’s too bad.  But, I’ll bet the next one you write will be even better!”  <grin>

Stunned I stared at him.  My boss, Bren, noticed my surprise and added, “We don’t count the number of home runs here, but the number of times at bat.”

The moral of the story

What you measure, you reward. What you measure, you encourage.
It’s not only about precise measurement; it’s how your culture compares and values developers.

How do explicitly and implicitly evaluate your programmers?

By the number of times, they knock it out of the park?
… or the number of times they bravely step up to the plate and swing for the fences?

It’s up to you.