He's also proven he can lead this team to failure. 7-9, 7-9, now 3-8. Thats a bad coach. 1 decent season(which ended in a first round playoff blowout) does not mean he can have 3 horrible seasons.
As far as the quarterback excuse is being thrown around: Tony Sparano decided that Chad Henne was his franchise quarterback. He was wrong. He deserves to lose his job based on that if nothing else. The losing seasons, horrible starting line-up decisions, and horrific game day mistakes are simply icing on the cake.
Tony Sparano opened this season with a handpicked coaching staff, with a draft and free agent period that he had say over(he had say in previous years to, but this was more official as it was written into his contract), and started the season with "his guy" at quarterback. The result was an 0-7 start and a 3-8 record. The man has had 4 years to clean up this mess. He has failed to do so.
Any excuse you want to throw up is completely undermined by the fact that we are 3-8. There are no moral victories in the NFL. We are a bad team being lead by a bad coach. You have provided no proof that Sparano can succeed on this team other then stating "other bad coaches have had success in the past with good quarterbacks". Fact is, Sparano had multiple chances to get a good quarterback. In usual fashion, he couldn't evaluate the talent on his team or in the draft correctly and it lead to failure.
But he's 3-0 in games where we ended up with more points than the opponent!