Let's think about this for a moment. While the Senator is choosing his/her nomination slate from the entire state.......that may not necessarily mean it is tougher to get a Senatorial nomination or that the slate is more competitive in general than a Representative's slate.
Here in Texas, the Senators check with the Reps so they do not duplicate nominations. So, if Senator X checks with the many reps across the state and eliminates those who are going to get a nom from any one of the reps from the applicants under consideration for Senator X's slate of nominees, the relative "competitiveness" of that Senator's slate could be very competitive or not so much. Not so much if the really awesome applicants had already been snatched up by the reps for their slates..........
I tend to think the competitiveness of any given slate of nominees is truly "pot luck" from year to year. Some years, the buffet may have lots of goodies, other years, maybe not.
Now, if the Senator had first choice of all the applicants in a state, then they would likely have the toughest, most competitive slate of nominees.
It is always true that on a competitive slate, you are only competing with nominees from your congressional district with the representative's nomination. For the one slot allotted to that MOC. Then the rest of the slate would go into the national pool. From there, depending upon how competitive each candidate is, there could be multiple appointments.
All of this analysis is designed to give us something to think about while waiting. And waiting. And waiting some more!