Is it an agreement though? Gylfi is all about Koeman. Koeman loves him.
So is an agreement or is it Koeman putting his foot down and Walsh saying "oh, ok then"? This is where things get complicated. There is only a certain amount in the budget. Will it affect a Walsh target? Will Walsh say to Bill to get the best deal possible so there's money left over for one of his players.
Then When team selection issues arise who is Koeman going to put in his team? The player he's always wanted (gylfi) or the rough diamond Walsh has scouted and brought in? This is where problems arise. It's all very well saying that they come to a joint decision but who has the final final say and who advises Bill as to how much we really want a player.
In my opinion the final say/lines of communication from manager to board have to be so clear, ideally written into contracts. If Koeman gets a whif that transfers are being deliberately slowed down to the point where they fail so alternative better-value players are brought (Walsh targets) he won't be happy.
The recent "7mil" jibe was his second go at the board this year. The director of football role can be successful but it can also create disharmony. I can't imagine that Koeman is the type of guy to bow to Walsh' superior knowledge. I can imagine Koeman being promised the world by Moshiri last summer and then bill trying to tempor expectations on budgets/wages offered to players.
Be interesting to see how things develop over the next few weeks...