How to insert two features in a model when a feature only applies to a certain group in the model
Remember that any model will have the relationships between the features (X) and the label (y), so your ideas are correct. What is better will depend on your data, so try both, and try more ideas if you can. The best model will be the one that generalize better for new data, so take the final decision with data.
Please, note that your features are at least 3, goals, goals_conceded and position, so this last will help with the problem.
And I suggest not to fill NaN with 0, but -1 (or any other imposible/invalid integer number), because a newbie player will have 0 in the feature(s), and it's correct, and you want to identificate this.