You may be right but I really don't know. Even if Tottenham signed the players Mourinho wanted, I'm not sure whether they would have managed to fight for the championship. Because I still don't like Mourinho's style which is generally ending mostly-attacking play after scoring 1 or 2 goals. Tottenham really affected badly by that also. With a more fitted manager, Tottenham could be much better than this. And of course, I think they need to strengthen their midfield.
I am not a fan of Mourinho but you underestimate his ability. He is one of greatest coach in soccer. Mourinho does not have good substitutes for Kane and Son. Bale came back too lately in this season. Bergwick is a failure as he missed many great opportunities and that partially contribute to some bad results for Spurs.
The team and Mourinho can not blame on Bergwick but if Spurs have at least one more player who can help them with goals, they will be more competitive.
On a very realistic note Tottenham does not have what it takes to win the EPL just yet, the truth must be told, the foundation of the team is built on Son and Kane, 98% of their goals are score by either Son or Kane which is not good for a team challenging for a trophy, the goal must be spread around, the midfielders, defenders must be on the score sheet more often .
Coaches can not play and score goals on behalf of players. They can build up tactics and training players to help them create pressure on opponents and create opportunities to score goals. But score or miss opportunities, it is the side of players. I see Spurs have scored a lots of goals and many opportunities were missed. It is not fault of only Mourinho.
take a look at Mancity and Chelsea team where the defenders and midfielders are always on the scoresheet every weekend, these shows how independent the teams are. Daniel Lavy needs to invest on quality players because coaches can't do it alone.
At least one more goal productive wingback and one younger central defender in the summer transfer.