Don’t hesitate to throw your change up with base runners on base. Too many times we are so concerned about giving our catcher good pitches, (faster pitches) to throw because we are afraid of someone stealing a base that we end up throwing a pitch that the catcher never gets to catch.
The hitter is likely to believe you are coming at her with your hard stuff when there are potential base stealers on base. Nothing gets a pop up faster than a hitter expecting heat that gets a change. Your job is to get the hitter first, foremost and always!