Yes, that's my opinion. A belief in that which has yet to happen.
To that effect, no one we sign or don't sign will guarantee anything. Do you generally assume when folks say, 'if Aguero can stay healthy, we will win the league' that they are stating a fact? Or simply an opinion they hold - even if you do share that opinion?
In this context, (I.e football discussions) facts are things that have happened. Opinions are things that you believe but are yet to happen or are unprovable at the time of stating them. Whether I believe it with an air of certitude is irrelevant.
It is not hard to differentiate btw the 2. But as a matter of detail, the 'definitely will with him' modifies the previous sentence. I was simply expressing my level of confidence, I.e. we likely will win anyways, but he is a good insurance we will.
But regardless of how you choose to read it. It is still an opinion.
BTW: are you MaineRoadblue?