[tempusalaria]

Fast tire changes only matter a very limited amount of the time (pretty much only if the extra time drops you a place, so there has to be 1 car/20 in a specific 1 second window on what is typically a 90s lap for 3s (a slow stop) vs 2s (a fast stop) to matter. Maybe 20% of the time a slow stop happens, it costs a driver.

Strategy matters a lot and good strategy is worth at least a few positions in a race.

[basisword]

You're forgetting the offset from undercutting. The cars don't need to be within 1s on track for it to matter - you could be within 4s and that extra 0.5s in the pit stop costs you the position if you pit later. Un-lapped 'traffic' is also critical. If you're trying to find a gap to pit into and it's tight an extra second could put you behind a slow car and cost you 'real' positions later.