So let's say we have a flap or slat lock. Or both. The pitch attitude on approach is higher.
All three cannot be considered in the same breath. Slats increase the attitude and flaps reduce it and together we get about +4 degrees on approach, not 2.5 degrees. If you only have slats it will significantly increase the pitch on approach. Something like eight degrees and that's why we need a small flare because tail strike can occur at 11.7. If you have slat jam the attitude is not a problem. If both are jammed the speeds are initially Vref+60 then Vref+50. There is no high angle of attack involved the speed increment takes care of that. It's V square remember?