Articulation in piano playing is exactly like articulation in speech. You’ve heard people that don’t pronounce each word, but slur words into each other. If it is extreme, their words are hard to understand. But you’ve also heard people that pronounce each word clearly –almost all good public speakers do that. Of course anything can be taken to an extreme, but as in speech, piano playing needs to be clean too — so each note can be heard and not all “muched” together. Listen to this short podcast and you will instantly understand.