I'm with S_L here; I don't think umpiring standards have slipped at all. Two things HAVE happened, though;
- Ability to pick up mistakes using technology made by umpires has increased exponentially.
- Based on that increased ability, the standard for 'good' and 'bad' decisions has correspondingly increased.
I do remember when seeing replays years ago (before 3rd umpires) where people would say something like "Oh well, that LBW, on replay, was relatively close but too close to give out." Now, the same LBW shout will be called a 'disgrace' just because Hawkeye says it was out. Umpires have a raw deal these days.
So, as I've been advocating for years now, forget sentiment and institute the use of technology wherever it can be (ie practical and accuracy considerations taken into account) and where it can't be, accept that umpires may make mistakes. Make all front-foot no-ball calls automatic (if the technology to do so is available), refer all stumpings , run-outs and disputed catches to the 3rd umpire (they virtually all go that way anyway so there will be barely any difference) and leave the field umpires to adjudicate LBW's and anything else that's left, accepting that humans make mistakes and until an acceptable alternative exists, they always will (Hawkeye doesn't count because it's an excellent guide but not a definitive tool for adjudicating LBW's/etc. just yet).