The PTAB is a “death squad” eager to cancel patent claims in IPRs.
Only 9% of all filed IPRs resulted in any patent claim being invalidated.
As of February 15, 2019, only 5,954 patents of an estimated 3 million patents in force had been challenged at the PTAB -- less than 0.2%.
Even fewer patents have been cancelled by the PTAB. As of Dec. 31, 2018, only 1,303 patents or about 0.04%—of active patents have been invalidated in a PTAB trial.
[Source: Data from Lex Machina]