That's right.
We must realise that pre-season games are sometimes just a warm-up for some big clubs because there are other things to consider such as giving opportunities to some players who rarely get this time to take precedence over looking at the schemes.
This is one way for the coach to measure how ready the players are after a long holiday.
Don't take friendlies and pre-season tours too seriously because sometimes they can be tricky and an example might be Chelsea and Liverpool in the season that has ended this time.
Pre season matches are exactly like you noted. A warm up for clubs and also to test player capabilities and fitness. Big clubs could also use pre season games to field players who barely see some action during the season and new tactics could be formulated and developed at this stage.
Friendly games are a great way to test player fitness and readiness but I also think it shouldn’t be used to predict or determine whether a club would be successful during that season. One could play very well during the pre season games and end up playing woefully during the entire season.