Explaining revocable waivers and post-deadline trades

Kemp's sac fly 0:24 8/5/15: Matt Kemp lofts a sacrifice fly to right field, scoring Alexi Amarista and giving the Padres a 1-0 lead in the 1st inningBill Center, longtime sportswriter for U-T San Diego, is an employee of the Padres.

I saw the apparent news this morning. Sources have told various baseball media people that the Padres have placed outfielder Matt Kemp and right-handed starting pitcher James Shields on revocable waivers. I have no reason to doubt those rumors.

A friend asked me, "What does that mean?"

My response: probably nothing.

First of all, the average fan would be surprised to know the names of all the players on waivers at this time of the season. On some teams, 100 percent…