I managed to find some statistics on hull losses per million departures [1, p. 13]. Seems like indeed MD-11s have a highish rate of incidents by that metric compared to other types, even if they are not catastrophically less safe than other planes. That metric stacks the statistics a bit against cargo planes, which most (all?) MD-11s are now. These planes tend to fly longer haul instead of short hop, so you get more flight time/miles but less departures. There are also likely some other confounding factors like mostly night operations (visibility and crew fatigue) and the tendency to write off older planes instead of returning them to service after an incident. Plus these aircraft have been in operation long enough that improvements in procedures and training would impact them less than more modern types, as in they already had more accidents before these improvements.

[1] https://www.boeing.com/content/dam/boeing/boeingdotcom/compa...

The DC-10 had a number of other problems, but the MD-11 has always had a reputation of being an unforgiving aircraft especially when compared to the DC-10. It's less about training and more that the MD-11 was simply too many design compromises piled on to an old design.

The MD-11 had a pretty short service life as a passenger aircraft because it simply wasn't very fuel efficient compared to the competition, safety wasn't really the motivating factor. However fuel consumption was behind some of the poor design choices McDonnell/Boeing made. In broad strokes: McDonnell/Boeing shrunk the control surfaces to improve fuel consumption "necessitating" poorly designed software to mask the dodgy handling and higher landing speeds. This exacerbated a DC-10 design "quirk" where hard landings got out of hand very quickly and main landing gear failure would tend to flip the plane.

Yeah you can train around this but when something else goes tits up you've got a lot less leeway to actually recover safely.