As long as there are humans umpiring, there will be mistakes. I have no problem with that. They won't be perfect at calling balls and strikes (and FTR, the automated balls and strikes call system isn't perfect either), but some umpires are better than others. For one, they could start by letting the umpires with the best track records officiate the postseason. That wasn't the case this year and usually isn't the case.
They could bring back those old huge chest protectors, as MVP mentioned before. That would give the umpires a better angle to call balls and strikes.