Exaggerated emphasis on stability and/or respectability or something like that, presumably.
You nailed it, basically.
The party hasn't mentally recovered from the major knockout that the 2009 election was. Since then the party is unbelievable unassertive and afraid to take any risk, even more so than before.
In case of the Saarland, it helps that the CDU there is probably the most left wing in Germany with traditionally strong roots in the catholic working class.