There is nothing wrong with the Flink runtime ;-) The Tez and Flink runtimes have a bit different design goals.
Flink places more tasks into one Jvm, streams data, manages its own cached results. Tez places a strong emphasis on elasticity, process Isolation, ... I think the two runtime are valuable in different environments, when different requirements dominate. That's my opinion on this, I am curious to hear what you think.
