Is this a balk?

[insatty]

In situation (b), the pitcher legally disengaged the rubber, so no balk.

In situation (a), the pitcher is deemed to have stepped either toward 2B or 3B under the 45-degree rule of thumb. OBR and NFHS permits the pitcher to throw, and presumably step toward, and unoccupied base for the purpose of making a play on a runner. Relatedly, the PBUC Manual says it is not a balk for a pitcher to step toward 2B and, discovering the fielder has not covered the throw, throw to a fielder not at the base. To me, therefore, this is no balk.