At my first management job, as an IT operations manager, I took over a large system from another guy who happened to be in the same team.
Good for him, he often went drinking with the guys who monitored the outages of the systems which resulted in not reporting his outages. Bad for me, I didn't knew anybody in the company (I just started) so the monitoring people switched to doing their job as they were supposed to do.
Reported outages went up, bonuses on higher levels went down and my boss passed on the pressure to me. She always praised "team spirit" so I was not sure how to defend myself.
What should I've done?
Take a stand
Couldn't you have developed a retrospective report to show how many outages went unreported previously and then explained that you were being more diligent in the reporting than the previous guy (at the pub) had been? Talk up your attention to detail and positive impact that identifying more outages overall has for the business.
Outages impact operations (and therefore the moneys). If the root causes aren't being fixed because they aren't identified because the outage isn't reported to management in the first place, then that's bad!
If the bosses didn't want to know about the real level of outages that were occuring because it impacted their bonus.. well thats an ethical dilemma right there - more bad :). I'm not sure I would want to work in an environment that put you in that kind of position.
Fix the problem
You can't say "but the last guy had it easy!" to your boss. You've been confronted with data of bad performance. The only thing to do is get better and look good doing it! Just because outages weren't "reported" doesn't mean they didn't affect someone's work day to day.
Solve the actual problem and see the efficiency of the whole org rise. If you are asked why, talk about what you did to fix the problem not about the guy who ignored it. Your bosses might find they get even better bonuses because of your hard work.
Don't get sucked into the vortex of hiding the problem. Be the org's hero!
Agree with previous comment
Agree with previous comment - you job is to show consistent improvements.
Identify root causes - do analysis - put actions in place - monitor outcome and repeat until you see better results!
Kind Regards
Mads Sorensen
Disc 4536