Sentence:  Ryne Duren and Roland Sheldon , a rookie righthander who posted a 15 - 1 record last year for the Yanks ' Auburn ( N.Y. ) farm club of the Class - D New York-Pennsylvania League , <WSD>are</WSD> the probable rival pitchers . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)