THIS has been the season of the ace, the go-to guy, the 20-goal striker.

The Clydesdale Bank Premier League may yet undergo serious remodelling, but this cycle, already defined by seismic change, is without precedent in goalscoring terms. Celtic have the title. Dundee are going down. The golden boot? Now there is a race.

Not once since the Scottish Premier League started has the top goalscorer come from outwith the Old Firm. Kris Boyd scored 32 in 2005-06, the season during which he transferred from Kilmarnock to Rangers, his goals split only slightly less than symmetrically between the two. That is as close as we have come to having a striker in a different shirt topping the list. Boyd and Henrik Larsson are giants in this era, with nine of the 14 titles between them, the Swede holding one more than the Scot.

Yet this season, the current front three in the race all come from clubs outside Glasgow. There is one good reason for this increased representation, and the absence of Rangers plays a bigger part than a brief analysis suggests.

Going into the weekend's fixtures, Billly McKay of Inverness Caledonian Thistle and Motherwell's Michael Higdon are tied on 20 league goals. One back is Leigh Griffiths of Hibernian, loaned from Wolverhampton Wanderers. On 16 are Niall McGinn of Aberdeen and Gary Hooper, last year's golden-boot winner, whose biggest goals for Celtic this season came in Europe.

The last striker to top the list from outside Rangers and Celtic was Tommy Coyne, with just 16 goals for Motherwell in 1995. Coyne's total tied for the lowest since 1903 to take the prize – Charlie Nicholas of Aberdeen and Celtic's Mark McGhee both hit 16 in 1989 – but he can also reflect on 1987-88, when he won his first golden boot with an incredible 33 goals for Dundee.

Since then, few have come close and in the SPL era only two strikers from outside the big two have broken 20 in the league. Derek Riordan scored 20 for Hibs in 2005; Anthony Stokes went one better for the same club in 2010. No other top-flight team has produced a 20-goal striker until this season, when four of them have a good chance of doing so.

Most seasons have ended with the main men at Rangers and Celtic dominating the list. Those who break in have a habit of moving on. Take as an example 2006-07, when four players ended up between Boyd, at the top with Rangers on 20, and Celtic's top scorer, Jan Vennegoor of Hesselink. Each of Steven Naismith (Kilmarnock), Chris Killen (Hibs), Stokes (Falkirk) and Scott McDonald (Motherwell) would find their way to Glasgow.

If those at the top of the list this season are to use their achievements to improve their prospects, it is unlikely to be by this traditional route. Only Higdon would fall into Rangers' apparent range as a free agent approaching the autumn of his career.

Celtic, meanwhile, have a different acquisition policy these days and their strikers are more likely to come from further afield. However, the one that fits their game most obviously is McGinn, a player they cut loose just last summer. It would take a transfer fee to get him away from Aberdeen in the middle of a two-year contract, but the Irishman has shown this season that he has the all-round forward game, as well as the goals, to win matches at this level and would be a sure thing domestically for his former club if they were to repatriate him.

McKay recently signed a new contract with Inverness, but Griffiths, in all aspects, remains a riddle. Including even Hooper, who will be pursued by Barclays Premier League clubs in the summer for upwards of £8m, the Hibs man has produced the most enthralling showreel, with his 19 goals featuring few from close-range. Instead he has scored from improbable angles, with daring free-kicks and has peppered goalkeepers: 50 of his 103 shots have found the target. Hooper, Higdon and McGinn all have better ratios, but take nowhere near as many shots. Griffiths is the wildcard; it is easy to see why Dean Saunders, the Wolves manager, wants to have another look at him in the summer, and why he will be so madly missed if he leaves Leith.

Who will win the race for the golden boot? It may come down to further analysis of a key factor in the increase in strike rate among the league's best forwards. With the collapse of Rangers, three games against the Ibrox club were replaced in this season's pre-split schedule by three meetings with Dundee. How much difference can three games make? Plenty.

All five of the runners have a strike rate of more than a goal per game in their matches against the Dens Park side. Hooper and Griffiths each have three from three against the bottom-placed side. McGinn and McKay have scored five in three, each with a hat trick. Higdon has three goals in two games against Dundee and Motherwell play them for the final time this afternoon.

Take away these fixtures and things look different. Higdon would be top on 17; McGinn would appear out of contention on 11 league goals; not one striker in the division would appear a nailed-on certainty to break 20, although Higdon, Griffiths (16) and McKay (15) would all hold that ambition.

So we reach the key variable in what is left of the season: the split. McGinn, four off the pace, will probably play his final five games against weaker opposition. That may still be too few games to overhaul the three strikers ahead of him.

However, today Griffiths and McKay go head-to-head at Easter Road. If Inverness help send Hibs to the bottom six, then Griffiths, too, will have a strong advantage, and could start the run-in on a par with his rivals. While they will play each other, he will be taking pot shots, free-kicks and penalties against the five worst teams in the division.

However it ends up, Higdon, McKay, Griffiths and McGinn have had the seasons of their careers and supporters at Fir Park, the Caledonian Stadium, Easter Road and Pittodrie have celebrated that rare thing: a striker you can believe in every other Saturday. Especially when Dundee come to town.