Your catcher can have a great influence on your work - especially the quality of your perception on how well your pitches are doing. In addition, based on where your catcher places himself behind the dish also influences the visual quality that’s passed on the umpire calling balls and strikes. The picture below will give a basic idea of how a catcher can influence your work on any given day/night.
http://i216.photobucket.com/albums/cc90/CoachBaker/catcher-1_zpswrpugjhf.png
** I should note that in competitive baseball, catchers are coached to distance themselves in relation to the batter more than just the plate. But that and other dynamics of catcher placement is beyond this simple basic approach.**