I believe a shortage of 105 drivers led to a large number of AT and 135 pilots being given crossovers to onto the Thud. They then suffered heavy losses due to their inexperience with the jet.
Story we heard at the time was that the USAF was run along the lines of once in SAC always in SAC, once on B47s always on B47s. When the 1600 B47s were retired there were an awful lot of spare aircrew with no need to transfer them to the Buff.
Also, since the Buff crews had a cushy job pulling alert in the US all the load was falling on TAC.
The solution, and the effect, was as you suggested. Not just lack of experience on the jet but lack of the whole single pilot tac stuff.