Chelsea were strongly interested in signing the 22-year-old, but Tottenham moved decisively to complete a deal worth around 60 million euros with RB Leipzig. Simons has endured a slow start in north London, failing to score in his first 10 appearances across all competitions, with his only assist coming on his debut against West Ham.
Despite that, Frank has insisted that patience is key and remains confident the Netherlands international will soon hit his stride.
"Yes, no doubt about that," said Frank when asked if he still believed Simons would be a success. "I'm not in doubt that Xavi will perform very well for us. That is down to him, to me, to the team, to everyone, to get it done.
"The one thing you don't have in football is time, but it will take time. It's completely natural. I'm confident. I'm sure it will happen."
Tottenham's struggles to create from open play have been a major talking point during the early months of Frank's reign, but there have been signs of improvement.
Simons produced one of his brightest displays in Wednesday's Carabao Cup defeat to Newcastle, showing glimpses of the quality that made him one of Europe's most sought-after young players, particularly in a new role as a double ten behind the striker.
"It's probably too much to put everything on Xavi," Frank admitted. "When this team was clicking well before, it involved Maddison, Kulusevski and Son all at the same time. It cannot be on one player, it needs three or four to get the team flowing."
Simons, who came through Barcelona's academy before spells with Paris Saint-Germain and Leipzig, is adapting to the demands of the Premier League, something Frank believes will take time.
"I think his fitness is growing, his intensity is growing," the Spurs manager added. "He's come to a country where you need to train and play with high intensity, and I'm asking him to work harder. Even though he's an experienced 22-year-old, he's still coming into a new league and country. That's very normal. But yes, I think he's taking steps forward."
Tottenham will host Chelsea on Saturday evening, with Frank hoping Simons can deliver the spark that gets his side firing again.
Mikel Arteta has described Granit Xhaka as "one of the signings of the season" ahead of Arsenal's reunion with their former midfielder when they face Sunderland at the Stadium of Light on Saturday.
Strasbourg's on-loan defender Mamadou Sarr has chosen to represent Senegal at international level despite having represented multiple France youth teams.
Jadon Sancho's struggles deepened on Thursday night as the on-loan Manchester United winger failed to seize his opportunity in Aston Villa's 2-0 victory over Maccabi Tel Aviv.
Oliver Glasner has praised Crystal Palace's fighting spirit but admitted his side "still have plenty to improve" despite a commanding 3-1 home victory over AZ Alkmaar in the UEFA Conference League.
