And he pointed to the latter’s contribution as a real stumbling block to making it a success.
The loanee duo have started the last two games together – and three of the last six games – in a new strike force made possible by the departures of John Marquis, Ellis Harrison and Gassan Ahadme in January.
However, it’s a partnership that has yet to catch fire in the style of Whittingham’s double act with Paul Walsh in the 1990s.
That saw him substituted in the 67th minute, ensuring his search for a Pompey opener extended into a sixth game.
Of course, the more the duo play together, the better their understanding in front of goal will be.
But, at the moment, that’s not working as far as Whittingham is concerned.
And he thinks Walker could do more to make it work.
He told BBC Solent after the win over Donny: “It’s not working for me”.
“I have to be honest here, I don’t see Walker getting involved in the builder’s play.
“I wasn’t used to it, it was Paul Walsh, I had a good partner with me, but I like to think I was at the end of things coming into the box.
“But Walker doesn’t even seem to do that.
“I don’t know what it is, if they haven’t gotten the right relationship, I don’t know.
“Hirst is happy to do all the racing and be involved in the builder’s play, and even if he gets it wrong, he’ll walk away.
“I really like that about him and that’s why I was happy that he scored his goal again today.
‘Walker just seems to be a little more laid back, doesn’t seem to want to get involved in build play, doesn’t react quickly to things for me in and around the box – and there’s a lack of chances coming his way .
“Yes, as a striker you want them created for you, but you have to create them, you have to race, you have to want to get into the box and dangerous areas, but I haven’t seen that again from him.