LOC definitely positively correlates to productivity, it just isn't everything. One year I modified over a million lines, because we decided that we wanted to stored some generated data in a config file that was checked into git, rather than in the DB. If you can ignore certain commits like this, the correlation is probably even better, but use it as just one data point.
Another major confounder is that super deep investigations that fix major problems often have relatively trivial solutions at the end. But the effort to debug and fix them (that is largely hidden by conventional metrics) is enormous. The people working on these types of things are often your best devs (because you know they will actually get to the root cause), but if you are only looking at LOC you wouldn't know that.
Another major confounder is that super deep investigations that fix major problems often have relatively trivial solutions at the end. But the effort to debug and fix them (that is largely hidden by conventional metrics) is enormous. The people working on these types of things are often your best devs (because you know they will actually get to the root cause), but if you are only looking at LOC you wouldn't know that.