Either Houston or San Antonio will win their division so one team will finish ahead of Portland in any three-way tie. Unless the Blazers manage to beat out Denver for the division they can finish no better than second.
The division-winner tiebreaking process supersedes the three-way tie process. In other words, a division winner is determined first between Houston and San Antonio and THEN the three-way tie between them and Portland is resolved.
Houston and San Antonio are tied for head-to-head record, 2-2.
The next tie breaker between them would be division wins. Houston stands at 8-6 against the division, San Antonio at 9-6. Houston's final two games of the year are division games (New Orleans, @Dallas). San Antonio has one division game remaining (New Orleans).
If the two teams remained tied after division wins are factored in then conference wins come into play. Both are 31-16 against the Western Conference with four games remaining.
If the teams still remained tied after conference wins the next tiebreaker is record against conference playoff teams. Houston is currently 13-12 with 2 games remaining against playoff teams (New Orleans, @Dallas). San Antonio is 10-13, also with 2 games remaining (Utah, New Orleans). The worst record Houston could finish with is 13-14, a 48.15% winning percentage. The best record San Antonio could finish with is 12-13, a 48% winning percentage on the nose. If the tiebreaker got this far, Houston would beat out San Antonio by .15% and take the division.
