Most dominant teams in stage races:
2013 (so far): Sky
Oman, P-N, T-A 2nd, Criterium International 1st & 2nd, VaPV 2nd & 3rd, Romandie, Giro 2nd, Dauphine 1st & 2nd, Tour.
2012: Sky
Algarve 1st & 3rd, P-N, Romandie 1st, 4th &5th, Dauphine, 1st, 2nd & 4th, Tour 1st & 2nd, Vuelta 4th. Podium in: Criterium International, Pologne, Burgos & Beijing.
2011: No team was really strong that year.
Toss up between Evans and Contador, both without any team member winning any stage race of note. Evans: T-A, Romandie & Tour. Contador: Murcia, Catalunya, Giro & Tour 5th.
2010: Astana or Liquigas
Astana: Algarve, P-N, Castilla y Leon, Trentino, Dauphine 2nd, Tour. Liquigas: San Luis, Sardegna, Giro 1st & 3rd, Slovénie, Burgos 3rd & Vuelta.
2009: Astana
Cali, Algarve, T-A 3rd, Castilla y Leon 1st & 2nd, VaPV, Catalunya 3rd, Lux 2nd, Dauphine 3rd & Tour 1st, 3rd & 6th.
2008: Astana
Cali, Castilla y Leon 1st & 4th, VaPV, Romandie, Giro, Dauphine 3rd, Suisse 2nd & Vuelta 1st & 2nd.
That was the passport era. Perhaps later I will take a look at the EPO-test era.