Questions have been asked as to whether a number of players who went deep into the tournament are now struggling with tiredness having not been afforded a proper rest.
Three Lions captain Harry Kane has been constantly knocking back suggestions that he is fatigued, while Southgate lost five members of his current squad through injury.
The English top flight returned on August 10, a week before LaLiga and with Serie A starting eight days later and the Bundesliga a full fortnight on.
Speaking ahead of England’s Nations League meeting with Spain in Seville tonight, Southgate said the Premier League is suffering as a result of returning just 26 days after the World Cup final.
“I think it’s psychological freshness, rather than physical. Everyone adapts their training load appropriately,” he said when asked if he felt players had started the season more slowly than in other years.
“But I think when you see the league, there are probably a lot of teams that haven’t started yet at the level when they are at their maximum. There have been lots of injuries across our league, I don’t know about the rest of Europe.
“It is a balance. I don’t really understand why our league started so early, but they did, so it is a really difficult situation for the clubs.
“Some of the clubs couldn’t field a team without... look at Tottenham, who had so many players in the semi-finals of the World Cup; they had to put their players straight into matches on the back of very little pre-season, so it was an impossible situation for the coaches really.”
Kane has not scored in his last six England games, again drawing a blank in Friday’s 0-0 Nations League draw with Croatia.
The 25-year-old was sporting heavy strapping on his ankle ahead of England’s training session at Ciudad Deportiva Luis del Sol – the training base of LaLiga side Real Betis – on the eve of tonight’s match.
But Southgate played down any injury concerns surrounding the World Cup golden boot winner and also confirmed Liverpool defender Joe Gomez will replace the suspended John Stones for the Spain test.
“Joe Gomez will be coming in for John,” he said.
“He’s in really good form for his club. His matches for us, against Spain and Brazil, have been really polished performances.
“He’s a young defender, but a very good defender. Good athleticism, uses the ball well. I’m looking forward to seeing him in this game. It’s another opportunity to look at a couple of younger players. We’re slowly building a squad who are comfortable at this level.”
Southgate did remain tight-lipped, however, on who would play in midfield in place of Jordan Henderson, who is also banned.
Harry Winks is a contender to win just his second senior cap as England seek their maiden win in the Nations League.
Spain will progress to the final stages of the competition with a victory and have won all three games under new boss Luis Enrique, scoring 12 goals in the process.
England, meanwhile, have just one point, the draw in Rijeka against Croatia preceded by a 2-1 home defeat to Spain last month.
Southgate has urged his players to be boldere this time around as they look to ease any fears of relegation out of League A for the next edition of the Nations League.
“Spain have a slightly different style to Croatia,” he said.
“We know their technical ability, but we have to cause them problems with the ball. We can’t just defend for 90 minutes.
“We were more comfortable in the last 30 minutes at Wembley, but we have to do that earlier in the game, be brave enough to use the ball well, and cause them problems.”