Yes that's how it works, talented players will normally increase their production if they play with better player, that's pure logic 101, unless there's a chemistry problem, like it seems there was between Ryan and Spezza (2 playmakers together is never supposed to be the best bet for chemistry). But they didn't play together much anyway. In Spezza's last season as a Senator and Ryan's first, the only season they played on the same team, they played ~10% of the time together (6.46% + 2.26% + 0.41%, etc). Coach PM quickly identified the chemistry of the MoToR line and kept them together for the most part.
Line Combinations - Frozen Tools
Anyway, I NEVER SAID IT WAS "SIMPLE", I don't think I was vague or using the wrong words, I said "PRETTY SURE", which means it's my opinion and it also implies that it's not 100% guarantee. But it means that I strongly believe that his production would be a tad better playing constantly (and then more minutes, better offensive situations) with Duchene and Dzingel rather than Tierney and Boedker. 2 excellent offensive forwards vs 2 average offensive forwards who are really not "finishers", which is something Duchene and Dzingel can do.
THEN, I said "I THINK" he'd be close to PPG playing MORE minutes with Draisatl and McDavid, which implies that again it's my opinion and that I was not 100 % ensuring that. But that's a bet I'd easily do if it was possible.
Actually, he's really not the same player now as he was when he started struggling here. He did have some good stretches during his first season in Ottawa but it didn't last and had problems with the coaching staff too, he was in the "dog house" quickly. The problem for Chiasson in Ottawa was the expectations, from the fanbase but probably also the team. He was seen as a very good prospect before his rookie season which didn't go too badly with 13 goals and 35 points (plus 6 goals in his first 7 NHL games prior to that).
But then he was the main piece obtained for a player who was important part of the Sens team for the decade. It's actually never ideal situation to be in, if it doesn't go well right away and it doesn't last, confidence issues can arise. Anyway, it took a few years and after re-establishing himself as a solid bottom-6 forward on the Flames and Caps, he's at least showing now that he can put the puck in the net if given the opportunity, which should insure him another NHL contract, probably for a few years. At 650 000$ this year, he's one of the biggest bargains of the year.