Was hoping at one point that Zeke Nnaji would be part of this class. Maybe he still will be - this is only the early/fall signing period. For example, for 2018, Strickland was not added until this past spring.
GBP, this means nothing at this point. Plenty of good teams like Illinois, Georgetown, Creighton, Indiana, NC State, Cincinnatti, etc. have only 1 recruit. B-Ball recruiting is all over the place with schools having anything from 1 to 7 players as part of the class depending on defections and graduations.
The Badgers also essentially have two kids they signed last fall with the express intention of red-shirting this fall so those 2 kids - Currie and Hedstrom are also part of this class. Combined with Wahl, they will replace the departing Iverson, Happ, Illikainen, and Thomas. I think this leaves the Badgers two short of the scholarship maximum if they don't get another player. (edit - they are 3 short for 2019 as I don't believe Anderson is on scholarship)
I also think they could have had another kid in the early period, but one of the kids they had targeted early has really stalled in his development so I think they may have cooled on him. Nobal Days from Racine was "hot" as a freshman but now is not viewed as highly and I suspect the Badgers backed off on his recruiting.
Pack is probably right in that they may have pulled up short intentionally. The 2020 class is really strong with Johnson and Davis as the top in-state targets and a few really good out-of-state targets. The only senior next year is Pritzl and there are no likely defections. Depending on what happens between now and the spring signing period with the 2020 guys they might still decide to add one more, or use their 3 available schollies for 2020. (edit - there might be a 2020 announcement coming "very" soon from what I've read. Let's hope it goes in UW's favor.)
As for Wahl, he seems like can play some SG or more likely SF. Might also get some minutes at PF if they go small at times as teams seem to do more often these days. A solid addition. Built in that Brusewitz and Krabbenhoft mold. Not sure he'll ever be quite as rugged as either of them on the defensive end and on the boards, but I think he may have a little more offensive ability.