What does the mixture of sources tell you about the way the reporter researched the story?

After reading the New York Times article "Gordon and Martinez Mull Their Futures as Yankees" By Tyler Kepner, i considered all of the sources that Kepner used. First of all, he talked about how Yankees pitching coach Mel Stottlemyre criticized Owner Geogre Steinbrenner, the author took a quote from Steinbrenner about the whole situation between him and Mel. The author researched his story by going to the main sources and getting quotes from them. He got quotes from George Steinrbrenner, the owner of the team. Tom Gordon, Tino Martinez, and Mel Stottlemyre. When speaking of General Manager Brian Cashman, who was not available for interview, the author used non-interview speaking sources when he said that Cashman was also planning to leave. Overall, the author went straight forward to research his story and invterviewed most of the sources directly.