Long, who had made just one substitute appearance for Burnley previously, came in for the suspended Michael Duff and enjoyed a very good first start in the first team. His performance won him the man of the match when he polled 25.0% of the vote.
That was ahead of midfielder Dean Marney who was second with a share of 18.9%, third place Charlie Austin who won 14.4% and Danny Ings, getting his first start of the season, coming fourth with 9.5% of the vote.
The results were somewhat different in the player ratings where four players reached a score of over seven out of ten to take the point winning places. This time it was Austin at the top with a rating of 7.24 out of 10.
Behind were the two central defenders with Jason Shackell just pipping Long. Shackell's rating was 7.13 and Long's was 7.11. Goalkeeper Lee Grant claimed fourth place with a rating of 7.11 out of 10.
The result means both Austin and Long win seven points towards the Clarets Mad Player of the Year. There are three points each for Marney and Shackell with both Grant and Ings winning one point.
It means just four points separate those in second to fourth place with Grant now four points ahead of both Marney and Brian Stock, but Austin's lead is now 33 points after he took his total to 99 points this season.
Tomorrow, within an hour of the final whistle, the vote will start for the Birmingham man of the match. It will run until the end of Christmas Day.
Below are the two results from the Watford game and an updated player of the year table.
MAN OF THE MATCH
25.0% - Kevin Long
18.9% - Dean Marney
14.4% - Charlie Austin
9.5% - Danny Ings
7.2% - David Edgar
6.4% - Kieran Trippier & Ross Wallace
4.5% - Jason Shackell
3.4% - Danny Lafferty
2.7% - Lee Grant
1.5% - Martin Paterson
PLAYER RATINGS
7.24 - Charlie Austin
7.13 - Jason Shackell
7.11 - Kevin Long
7.07 - Lee Grant
6.89 - Danny Ings
6.76 - Dean Marney
6.54 - Kieran Trippier
6.46 - David Edgar
6.22 - Danny Lafferty
5.98 - Ross Wallace
5.37 - Martin Paterson
CLARETS MAD PLAYER OF THE YEAR
99: Charlie Austin
66: Lee Grant
62: Dean Marney & Brian Stock
40: Ben Mee
39: Michael Duff
30: Chris McCann & Jason Shackell
29: Kieran Trippier
18: Brian Jensen
15: Joseph Mills
14: Junior Stanislas & Sam Vokes
11: Danny Lafferty
10: Martin Paterson
7: Kevin Long & Ross Wallace
6: Marvin Bartley
3: David Edgar
2: Steven Hewitt
1: Danny Ings