No, Stick put together the core. Watson took over in the offseason of '96 and was responsibl for the deals to get Fielder, Hayes, Lloyd, Weathers,etc... Watson made great deals to help us win in '96 but it was Stick who put together the core.
Watson had some issues with Steinbrenner, and eventually was replaced, after 1997 I believe. Cashman replaced him. Watson is in teh Commissioner's office, and is no doubt much happier, and less stressed out.
He made some nice subtle trades during his tenure, bringing in little pieces to fill in holes. At that time, there was less of an influence from the Tampa offices, so the NY office was able to run the Yankees. Now-a-days, this is not so.
Stick Michael is the man! He's the reason we won 4 championships. When George was suspended from baseball, Stick took over and made good trades while also developing the farm system. At one point, the Yankees almost traded Pettitte and Mariano for David Wells but didn't. Another time George ordered Stick to trade Bernie Williams and Stick lied to George saying none of the other teams were interested. George realized Stick was lying and put him in the dog house. The only reason he was retained was to keep him away from other teams, most notably the red sox. Thankfully he seems to be back in the mix and hopefully Crazy George will listen to him.
As far as the job Cashman has done, it's hard to tell because so many times he doesn't make decisons and players just fall in his lap. For example, Cash had nothing to do with Wright, Woemack, Sheff, Chris Hammond and others. I know his offseason plan a couple seasons ago was to sign Guerrrero and Kaz Matsui to play 2B, and moving Soriano to CF or including Soriano in a trade for Beltran. Obviously, Kaz not happening was good but not having Vlad and a centerfielder at this time is hurting. I do know that Cashman wants the team to be younger and good defensively, which is why I think he's a good GM, but it's hard for him to not be able to do what he wants to do.