Grant Hardy has a great argument that verse 16 should really be between 12 and 13. It makes a lot of sense, and he gives examples of how verses are moved by accident in the Bible during transcription. I agree it works to strengthen faith in the book being of ancient origin.
However, theologically, I think it can work where it is just fine. That sounds crazy at first, to anyone who has read Alma 13 half a dozen times and then read Hardy’s article. But, with all the work we are doing on Alma 13 at Dews from Heaven, I think I can argue that it’s just as likely that it belongs right where it is.
First, Grant points out that it doesn’t seem to be necessary where it is, and that it breaks the flow of the verses around it. That is one good reading, but, another reading is that verse 15 actually breaks the flow of the verses around it. If that verse were to be put in parenthesis, it would read like this:
8 Now they were ordained after this manner—being called with a holy calling, and ordained with a holy ordinance, and taking upon them the high priesthood of the holy order, which calling, and ordinance, and high priesthood, is without beginning or end—
9 Thus they become high priests forever, after the order of the Son, the Only Begotten of the Father, who is without beginning of days or end of years, who is full of grace, equity, and truth. And thus it is. Amen.
10 Now, as I said concerning the holy order, or this high priesthood, there were many who were ordained and became high priests of God; and it was on account of their exceeding faith and repentance, and their righteousness before God, they choosing to repent and work righteousness rather than to perish;
11 Therefore they were called after this holy order, and were sanctified, and their garments were washed white through the blood of the Lamb.
12 Now they, after being sanctified by the Holy Ghost, having their garments made white, being pure and spotless before God, could not look upon sin save it were with abhorrence; and there were many, exceedingly great many, who were made pure and entered into the rest of the Lord their God.
13 And now, my brethren, I would that ye should humble yourselves before God, and bring forth fruit meet for repentance, that ye may also enter into that rest.
14 Yea, humble yourselves even as the people in the days of Melchizedek, who was also a high priest after this same order which I have spoken, who also took upon him the high priesthood forever.
(15 And it was this same Melchizedek to whom Abraham paid tithes; yea, even our father Abraham paid tithes of one-tenth part of all he possessed.)
16 Now these ordinances were given after this manner, that thereby the people might look forward on the Son of God, it being a type of his order, or it being his order, and this that they might look forward to him for a remission of their sins, that they might enter into the rest of the Lord.
“These ordinances” could easily refer to the ordination of Melchizedek to be a high priest and to take on him the high priesthood. Earlier in verse 8, the word “ordinance” was used without the antecedent being the washing clean of garments, which is what verse 16 would seem to refer to if we put it after verse 12. Being where it is, and with verse 15 bracketed, “ordinances” refers to the same thing it has throughout the chapter so far: the ordaining of priests to preach the gospel.
If verse 16 is left where it is, then the ordinances given after this manner (same as always, an ordinance to preach b/c ordained after the holy order of God) then it justifies what Melchizedek did with his people. The “the people” here refers to his people, already talked about in verse 14. Melchizedek was set up as a priest so his people could know to look forward to God. Then we see the story play out, and that it worked. The people repented and had peace (is it implied that they did enter into his rest?). So verse 16 actually could work great to set up why Melchizedek, a figure they have heard about, could have preached and called repentance. What follows after 16 flows from it because we see what happened in light of his ordination.