YOU know when two buses belonging to the same company are passing and the drivers give each other a friendly wave? That’s Glasgow Warriors and Edinburgh, that is, and no prizes for guessing which bus is going steadily uphill and which has embarked on a gentle but definite decline.

Or at least, there was significant evidence in the weekend just past to suggest that, come the end of the season, if things continue in the same vein, we can look back on Edinburgh’s victory over Munster and Glasgow’s loss to Leinster and say yes, that’s when the change became marked. That was the two teams’ bus-driver moment.

Not that anyone in the Warriors camp was waving cheerily at the end of a game that saw them slump to a fourth defeat in seven PRO14 matches. Leinster had not won at Scotstoun in seven years, a period in which they have won the Champions Cup and the Challenge Cup as well as the league itself, yet here was their second string turning up and, after a shaky start, bossing the second half to beat their hosts 23-10.

HeraldScotland:

READ MORE: Duo set for Scotland 7s debut in Dubai

Of course, that result highlights the remarkable strength in depth available to head coach Leo Cullen, but remember when that was always cited as one of Glasgow’s great strengths? It certainly doesn’t look that way this season.

Yes, there were players out injured, and yes, Dave Rennie opted to make some changes, but on paper this was close to the Warriors’ first-choice line-up. Closer, at least, than the Leinster select, in which not a single man had started the previous week’s European game against Lyon.

On paper at least, Glasgow are still in contention for a PRO14 play-off place, and, having beaten Sale then lost to Exeter, go into the double-header against La Rochelle with their hopes of qualifying for the Champions Cup quarter-finals still intact. And although their current run of form is concerning, it is nowhere near the nadir that their longer-serving fans will recall: the days of turning out in front of a couple of thousand at Firhill, or, further back still, of going down to places like Leicester and being utterly humiliated.

Even so, we are beginning to see the signs of dissent and dissatisfaction among the support for the first time since those far-off days. The bulk of the fan base may remain optimistic for the time being, but the difference between this season and previous spells of poor form is that now they can only hope that better performances will be just around the corner. Previously they could be all but certain that such an improvement was on the way.

Of course, what made matters worse for Glasgow on Saturday night was the fact that, the night before, Edinburgh had beaten Munster in Cork for the first time in 15 years. That statistic is a wee bit misleading given it is only five years since they won at Munster’s other home venue, Thomond Park in Limerick, but it is nonetheless a sign of a team who are maturing psychologically.

The fact that the winning score in the 18-16 result came from summer signing Eroni Sau was another indication that Richard Cockerill’s squad are moving in the right direction. The Fijian winger, who juggled Blair Kinghorn’s kick through before touching down, has already shown in his early games for Edinburgh how effective he can be in defence, with his kick-chase bodyslams demonstrating why he is nicknamed the Sledgehammer.

HeraldScotland:

READ MORE: Glasgow 10 Leinster 23: Champions just too hot for Warriors

If he can continue to finish as well as he did on Friday night while also keeping up that brutally effective standard of tackling, Sau will surely be seen as one of the best of the season’s new recruits in the PRO14. Although you do worry that, if his form drops at all, that slightly bombastic nickname may come back to haunt him. Remember Brendan Laney? Back in 2001 he arrived at Edinburgh bearing the nickname Chainsaw because, it was said, of his ability to cut through defences. Just to make sure he did not get too carried away, however, his team-mates soon christened him Coleslaw instead.

You suspect, of course, that Cockerill will ensure that both Sau and everyone else in the Edinburgh squad keep their feet firmly on the ground. Similarly, Rennie is the type of coach that keeps his players down to earth. The crucial difference after the weekend, however, is that those Edinburgh players will have that extra ounce of spring in their step, while their Glasgow counterparts may well be feeling a little leaden-footed.