More than twenty attempts reigned down on Ben Foster's goal at the DW Stadium this weekend, but only McArthur's close range tap in managed to cross the line.
Meanwhile at the other end, West Brom managed to find the back of Ali Al-Habsi's net after just a handful of attempts.
This gulf in finishing highlights the problems presently facing the Latics if we are to survive for an eighth season in the top flight.
It was completely one-way traffic on Saturday with Roberto Martinez's side dominating possession and territory against a Baggies team who have little to play for.
Roy Hodgson has managed to pull a very poor looking West Bromwich Albion team up to 36 points and a very safe looking position in the league.
At the same time, the Latics are left struggling in the relegation zone, despite on paper having a very decent looking squad.
The key difference between the two sides is defensive steel. The Baggies are not easily beaten as was evidenced by the Latics.
The performance of a team like West Brom this season could, and should, be looked at by ourselves to analyse where we have gone wrong.
In short, Roy Hodgson's side have managed ten Premier League victories in comparison to our four. This difference equates to eighteen points and explains the present disparity in league position.
Only after witnessesing such dominance from the Latics did it hit home that once again we have only taken a share of the spoils. For as much as Robreto talks about our dominance and excellent performances, it is points that are going to keep us in this league.
Victories against Swansea, Norwich, and on Saturday against West Brom would have the Latics on 29 points and well on their way to safety.
It is easy to point the finger at the manager, but he could not have predicted such poor displays in recent weeks from some key players within his squad as disappointments from key players continue to pile up for the Latics.
Hugo Rodallega sat out the fixture with a suposed knee injury. Following his absent display against Norwich less than a week earlier, the injury is either fair explanation for his dismal display of a cover-up for the Columbian's ego at once again being dropped.
Meanwhile Ali Al-Habsi must take blame for the Baggies equaliser. Not only was the Oman international stood behind his own goal line as Paul Scharner scored, but the cross which the Austrian converted was allowed to travel freely across the six yard area. Premier League goalkeepers need to take ownership of anything that enters their six yard area.
Meanwhile it was with great amusement that the crowd witnessed Gary Caldwell's outburst at Maynor Figureoa following the latters dismal free-kick at goal in the second half. Perhaps the Scotish centre back would be better focussing his energy's on learning how to defend as it is his guidance that has lead the Latics to their worst defensive performances whilst in the top flight.
It isn't all doom and gloom. There are some very difficult immediate fixtures coming up but this gives the Latics some no pressure games where they are expected to lose.
Any points picked up from games against Stoke City, Arsenal, Chelsea, Liverpool, and Manchester United can be considered bonus points before the crucial run in of Fulham, Newcastle, Blackburn, and Wolves.
Swansea aside, the Latics have certainly been improving over recent weeks and Roberto Martinez is hopefully right when he says that the all important elusive victory is just around the corner.
What better time to upset the red half of Liverpool that this Saturday with a shock away win to boost the points total. If we're to have a hope we need to get our defensive house in order.
