Yes, Humphrys has a poor cross-examination technique. The old saying is that 'cross-examination' does not mean 'examining crossly'. Talking over the answer as much as he does comes across as that. The cross-examiner is not meant to be the subject, either. The very best appear to be having a friendly conversation with the witness.
The problem the interviewer has on TV is the time limit. There's usually only a set few minutes. Politicians are adept at time-wasting by evasive waffling and answering the question that they would like to have been asked, rather than one they are to answer, until time is up. Some firm control of the interviewee is needed, which may mean stopping the flow quickly, and bringing him back to the question. Eddie Mair is good at that, without the Humphrys flaws