First-half goals from Josh Morris and Mark Roberts gave Alexander’s side a comfortable lead, and they secured their place in the top 10 despite a late goal from Michael O’Connor.
Alexander was full of admiration for a group of players who consolidated their position in League One after last year’s promotion, but admitted he will immediately be forced to consider which players to keep on ahead of next season.
He said: “I’ve got massive respect for every one of those players in the dressing room. They have all been fantastic and I’m proud for what they have achieved.
“But it’s a tough time for me as a manager and I’ve got some tough decisions to make. For the next 24 hours we will enjoy what we’ve done this season, but then it will be time to get down to the important work.
“We were all determined to end this season with a win and we’ve done that. We deserved the victory for the way we played and for the spirit and the application of the players.
“This is the biggest pitch in the league and the work-rate of the players with and without he ball was tremendous. We got the two goals and then gave Vale very few chances to get back into it.
“We defended brilliantly to a man. Vale have got players like Tom Pope and Mark Marshall who can hurt you, but all of my players stuck to their task manfully.”
Port Vale manager Rob Page added: “It’s a disappointing way to end the season, but it looked like one game too many. The lads have put an enormous amount of effort into the last few games to make sure we are safe and that showed today.
“We were all over the moon after winning at Yeovil last weekend ensured we were safe and we failed to reach those levels of intensity today.
“I could have made eight substitutions at half-time because so many of the lads were not on their game. But that’s not meant as a criticism because the attitude of all of them has a been commendable since the day I took over.
“It’s a bit of a let-down for it to end like this, but we are in this division next season and that is what matters.
“I’ll be talking to the players in the next few days because there are a lot of things to sort out. We’ve now got to plan the way forward.”