A statement of truth or a wasted opportunity. Lambda helper functions reluctant to return 2D arrays.

Thank you each for contributing to my continuing education!

At first I was distracted by the MAKEARRAYs but then realised the answer lay in the use of MAP.   I guess the key to generating a 2D array is that the array parameters must be of the same shape.  

= LET(
    teamList,  UNIQUE(team),
    teamScore, MAP(teamList,SCOREλ),
    teamOrder, SORTBY(teamList,teamScore),
    team,      IF({1,1,1,1},teamOrder),
    place,     IF(ISTEXT(teamOrder),{1,2,3,4}),
    MAP(team, place,
      LAMBDA(t,p,INDEX(MEMBERSλ(t), p))
    )
  )

I have shortened the worksheet formula by moving the formulae that extract arrays from the original rawdata to global defined names along with the definition of the Lambda functions.