The first evidence was that of Michael McKay an oil rig worker who observed a fireball in the sky exactly where MH370 sent it's last transponder signal. 
The debris that looks like that of a Boeing 777 was photographed by Vietnamese aircraft, then a Chinese Satellite and then observed by a Cathay Pacific Aircrew. All observations were EXACTLY where the DEBRIS was expected to be allowing for ocean currents that move at around 3 knots, that's around 75 miles a day or 150 miles in two days. 
That very credible and reliable evidence says it Exploded in a Catastrophic Disintegration when its transponder and ACARS stopped transmitting. NO Underwater search was commenced. Malaysian search incompetence failed to recognize the ocean currents, or the evidence of Michael McKay.

Now, they provide Satelite "Pings" that are anything but conclusive as there are denials, admissions and now more denials with an explanation. 
It's you believe the Malaysian conspiracy theories for Ordinary Normal Catastrophic Disintegration that has happened regularly for many decades. 
The De Havilland Comet had its first airframe failure in 1953, it too was first observed as a ball of fire. 
Now Boeing are crossing their fingers, Just like De Havilland did with their comet and if there is another Boeing 777 suddenly disappearing, then perhaps the penny might drop. 
This disintegration could also be the result of non-airframe causes, perhaps a boat fired an surface to air missile, or there was a mid air collision that was not revealed. That however borders on so remote as to fall into the remote causes promoted by Malaysian Air.