Sorry but no way is Kennedy a top 20 prospect, he'll probaly get in the top 50 but his ceiling isnt that high, probaly a #3 SP. Tabata is a solid prospect probaly in the top 35-30 range although hes still fairly raw and hes only 18 years old, he has a while before hes in the majors. No way does any Yankee pitching prospect other than Hughes even compare to Buchholz right now and his value to begin with. Chamberlain is rising he could eclipse top 35-40 by seasons end. But whats stopping the Dodgers from centering a deal around some package of Broxton (an extremely good young MR/CL), Laroche (a top 10-15 prospect), Kershaw (another top 15 prospect), or include Billingsby, Kemp, Either? No way the Yankees could top something like that without Hughes. Santana is the best SP in the majors bar none and hes in his prime. The Twins will want and get major league ready talent and a handful of top prospects. You saw what FLO got for Beckett and Hanley/Sanchez > Tabata/Kennedy and Santana is on another level than Beckett was. Your dreaming if you think Tabata/Kennedy is a better package than Buchholz/Ellsbury but thats beside the point.
EDIT: Hughes/Tabata/Chamberlain vs. Buchholz/Ellsbury/Bowden is pretty close. Yanks have an edge in Hughes vs. Buchholz but if Hughes ends up being out for the year or any large amount of time which is possible the gap is closing as Buchholz continues to dominate and keeps improving his FB command (Buch is already a top 10 prospect and close to top 5 depending on if you count some graduated spects). Ellsbury vs. Tabata is also pretty even (both in the top 30 range and improving), Tabata has the higher ceiling but Ellsbury is far more likely to reach his and hes still a potential all-star. Considering Hunter is a FA, the Twins would probaly view Ellsbury as more valuable to them in a deal. And Bowden vs. Chamberlain is pretty even, probaly give the edge to the Red Sox considering age although both are potential aces. I doubt either team offers these but theres no way the Yankees could possibly top our top 3 without Hughes and even then its close, guys like Marquez/Garcia/Wright are decent/intriguing but not deal breakers or premier talent.