The parallels between these clubs, similar in size and enjoying what by any standard is an outstanding season, are obvious, but so, too, are the contrasts, and it was the latter that made this a fascinating contest.
That Albion, having been outplayed and gone behind in the first half, should ultimately take the three points demonstrated the resolve that has characterised their progress under Steve Clarke, but they were also handed a huge slice of good fortune when a legitimate Swansea equaliser was wrongly ruled out shortly before the final whistle.
The Swans manager, Michael Laudrup, as measured in his opinions as he was with his passing, found it very hard to understand how Roland Lamah could have been flagged offside when, having pulled the ball back across goal, it was returned to him by a combination of the Albion defender Gareth McAuley and goalkeeper Ben Foster. The young winger duly turned it into the goal but the flag went up and the referee, Lee Mason – who had a horribly uncertain game – did not wave it away.
"How on earth do they disallow a goal when the ball comes off two opponents?" asked Laudrup. "It's like giving an offside after a throw-in. Everybody knows you can never be offside if the ball comes to you from an opponent. Either they don't know the rules, which can't be true, or they haven't seen it. I hope it's not the first."
Unfortunately for the officials it was not as if there was a Swansea player close to McAuley or Foster, as the Albion manager acknowledged. "We got a lucky break, it was a goal, it should have been given, but we still deserved to win the game," Clarke said.
A draw would have been a fair result, because while the teams may have been matched in formation, there was no question which looked the more tactically and technically accomplished in the opening period. The style and comfort with which Swansea retained possession induced an almost awed hush at the Hawthorns, and it would have become even quieter had Michu taken one or both of two excellent early opportunities. The first, ending a move he had begun, he volleyed wide from inside the penalty area, but the Spaniard looked certain to open the scoring when a wonderful passing move begun on the edge of Swansea's own penalty area culminated in Luke Moore leaving him with only Foster to beat. Michu's own team-mates were not the only ones taken aback when he poked the ball wide.
It was no surprise when the visitors took the lead. What was a surprise was the manner in which they scored, Moore escaping McAuley's attentions to head Jonathan de Guzman's corner home.
Remarkably, however, Albion levelled before half-time. Starved of possession though he had been, Romelu Lukaku is always a threat. A ball down the right gave Graham Dorrans enough space to cross low across the six-yard line, and the on-loan Chelsea striker slid in ahead of Garry Monk to turn the ball in.
The second half was a different story. Albion ripped in to Swansea and should have gone ahead when Mason adjudged Wayne Routledge to have tripped James Morrison inside the Swansea area. Lukaku's spot-kick was a poor one though, and Vorm, diving to his right, saved comfortably.
On the hour they did take the lead. Chris Brunt's corner was headed past Vorm by McAuley, and though Angel Rangel headed the ball off the line, the ball hit De Guzman's back and rebounded into the goal.
Swansea revived after Laudrup made three changes and Albion began to look increasingly nervous, but the officials preserved a win that takes the Baggies into seventh. "A really good game between two sides having a really good season," said Clarke, and that at least was unarguably true.