Tandy has opted for a more settled look to his squad so far, starting with the pre-season games against Worcester and Bath last month, and both men believe that consistency has given them an edge early on in the RaboDirect PRO12.
"Last season we were probably looking at giving more opportunities to players throughout the squad in the opening few games but this year we are being far more game specific and picking teams to get the result," said Tandy.
"This season we have a relatively healthy squad and there's real competition. The British & Irish Lions boys have also returned and brought a real energy into the environment.
"This season we have gone away to Treviso without any Lions starting and the boys put their hands up. We then went to Leinster and picked up two points, with the second half a huge positive.
"And we made sure we dealt with Edinburgh in a really good manner. It's not often we finish teams off like that. We feel we still have to get better as a group, with huge improvements still to be made, but we also believe we are in a reasonable place."
"We were probably a little bit more elitist in terms of putting people on the park for the Worcester and Bath friendlies," added Rees.
"Last year we played Clermont in early August and we pretty much put a squad side together when they were on the cusp of the Top 14 season, so that stretched us a bit. Then we chopped and changed in the Bath game at the Liberty in what was our last prep before the opening Treviso game last year.
"This season, we wanted to put key combinations in early and the two pre-season games were really physical workouts. We were able to bring 13 or 14 forwards up to speed early on in our preparations and we've used that as ammunition for the Treviso game and then for picking up momentum thereafter."
As for this week's action, Wales and Lions openside Justin Tipuric is set to start his first game of the campaign against Connacht on Saturday night.
His Lions colleagues Ian Evans, Richard Hibbard, Adam Jones and Alun Wyn Jones all begun the win over Edinburgh, with Tipuric coming on as a late first-half replacement for the injured Tom Smith.
Tipuric faces a big battle with the improving Sam Lewis for the No7 spot in the opening Heineken Cup clash with Leinster at the Liberty Stadium on October 12 and Tandy plans to play him from the off in Galway.
"It's really important to get Tips up and running. He's desperate to play for the Ospreys, which is huge for us," continued Tandy, who will have injury victim Tom Haberfield back in contention for the scrum-half spot at The Sportsground.
"He's a world-class player and always adds value. He can play in the centre, that's how good a footballer he is. He's destructive in defence, he reads the game, and he's a smart guy. He's had an amazing year.
"Sam Lewis has put a marker in the sand. He has been outstanding in the first three games.There's a world-class Lion in Tips but Sam is developing at a hell of a rate of knots and it's great to have that sort of competition in your squad.
"Tom will be available for us this weekend, which is a positive. Hopefully, Rhys Webb will be back earlier than we thought, too, so we'll have three outstanding nines providing competition for each other in all tournaments."