You make it sound like he was a terrible player - if that is the case why did Slade offer him a new deal - and was in discussions with his representatives months before? It wasn't so the club could get a fee - his age meant we would get cash.
When Porter broke into the team, we were in a really bad position. No, he wasn't Championship class either, but he he offered the team something different. Should we care that he wasn't the most popular guy? Ben Chorley wasn't either, but it's still possible to respect him and say he did a job.
He did OK for us in his spell - seems stupid to call him out for errors considering he was a rookie, plus the fact that the whole team were leaking goals at the time. Did people give Lee Cook the same stick for his lack of defensive duties? Why pick on a kid then?
I digress. The facts show his contributions triggered:
1) A club in a higher division offered him a three-year deal
2) Leyton Orient also offered him a new deal
Look at players past. Players that O's fans said 'he is great and will make it': Harry Beautyman, Soloman Shields, and so on. All released with very little chance in the team.
The fact that Porter got offered deals like this and the amount of appearances compared to other youth suggest to me he was a 'promising player'. Clearly Slade and Ipswich thought so too at the time.
Or wait, maybe your intelligence is higher than theirs or mine and I have missed something? Doesn't look like it, does it?