Sentence:  But Schnabel was a great teacher in addition to being a great performer , and the fact that four of the ten versions I listened to <WSD>are</WSD> by Schnabel pupils ( Clifford Curzon , Frank Glazer , Adrian Aeschbacher , and Victor Babin ) also sheds light on the master 's pedagogical skills . 
Meaning of the word marked with <WSD> tags:  be identical to; be someone or something