An Expected Goals on Target (xGOT) Metric as a New Metric for Analyzing Elite Soccer Player Performance
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsRecommendation for authors
The authors mentioned that: “Data for Spanish teams was collected from the statistical website Football Reference 80 (https://www.fbref.com), which used a comprehensive dataset from Opta (Stats Perform) (www.fotmob.com).” . You had an agreement from the website to access the data?
It is not clear, for me, what were the data extracted from the website and what is the connection/relation between this data and the analyzed variables (Goals, PV, xG, xGOT).
Goals is a calculated variable?
How was Possession value (PV) defined / calculated?
The authors mentioned that: “Expected goals (xG): is the estimation the probability of any given shot being converted to a goal based on various different factors describing the shot.”. Which are these factors?
The authors mentioned that: “Expected goals on target (xGOT): it’s an indicator for how well a player is shooting.” How is this variable calculated?
How was the data distribution? What tests did you use in this regard?
In the Results section, only some tables are presented without explaining the results obtained.
In the Discussion section the authors mentioned that “This model is called the “chain to goals model” (figure 2) and is based on the use of the four metrics analyzed in this study. The optimal model built in this project based in this 4 metrics may be more competitive when compared to previous metrics within the existing literature.[18-20] The accuracy of this model is evaluated statistically and is based on conversations with professional match analysts.”.
What does it mean “competitive when compared to previous metrics” - give more arguments / comparison with previous metrics.
Where is the accuracy of this model evaluated statistically?
What does it mean: “The accuracy of this model ……. is based on conversations with professional match analysts”?
Bibliographic sources should follow the reference guide.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
Congratulations on your effort, but in order for the article to be published, major revisions must be made, as noted below.
1. In line 33 of the introduction, you refer to a binary metric (goal or no goal); however, the way goals are mentioned in the previous sentence, they are not a binary variable, as the total number of goals a team scores determines the winner of a match.
2. In many parts of the text, the period (.) is placed before the relevant citation referring to the sentence (citations 2, 3, 6, 10, etc.).
3. There is no mention of data reliability verification. How do the authors know that the fbref data are reliable? If reliability verification cannot be done or there are no arguments for it, it should at least be mentioned in the Limitations section. I would advise you to look at the article by Kapsalis et al. (2023)
4. Readers do not fully understand what exactly Possession value is and how it is calculated. Instead, in line 94 of the Methodology, it is generally stated that Possession value (PV) measures the probability of a team scoring from their possession. How is it measured, though?
5. In Tables 1 and 3, there is an overlap of words in the first column.
6. In Figure 1, the word GOALS is not fully visible in E. Also, E appears twice, and there is no F.
7. There is no mention of whether a normal distribution test was conducted on the data. If not, how was Pearson's Correlation chosen over Spearman's Correlation, and how was the R² calculation performed?
8. In the limitations, it could additionally be mentioned that the study was conducted using a static rather than a dynamic method (Plakias et al., 2024; Pratas et al., 2018; Prieto et al., 2015)
9. Why is the fact that the researchers described a new metric (xGOT) considered a practical application? (lines 283-285)
10. In the Data Availability Statement section, the authors state that "Data are contained within the article." However, not only are the data not mentioned within the article, but the sample used is also unclear. What was the total number of observations (cases)? Was there one observation (case) for each team or for each match? Therefore, given that fbref data are freely accessible to anyone (so there are no ethical reasons), the authors should provide the exact dataset they used in some public data repository.
11. Finally, the use of the English language in the text needs significant improvement.
REFERENCES
Kapsalis, M., Plakias, S., Kyranoudis, A., Zarkadoula, A., Lathoura, A., & Tsatalas, T. (2023). Exploring the impact of possession-based performance indicators on goal scoring in elite football leagues. Journal of Physical Education and Sport, 23(8), pp. 2004 - 2015. https://doi.org/10.7752/jpes.2023.08231
Plakias, S., Tsatalas, T., Armatas, V., Tsaopoulos, D., & Giakas, G. (2024). Tactical Situations and Playing Styles as Key Performance Indicators in Soccer. Journal of Functional Morphology and Kinesiology, 9(2), pp. 88. https://doi.org/10.3390/jfmk9020088
Pratas, J. M., Volossovitch, A., & Carita, A. I. (2018). Goal scoring in elite male football: A systematic review. Journal of Human Sport and Exercise 13(1), 218-230. https://doi.org/10.14198/jhse.2018.131.19
Prieto, J., Gómez, M.-Á., & Sampaio, J. (2015). From a static to a dynamic perspective in handball match analysis: A systematic review. The Open Sports Sciences Journal, 8(1). https://doi.org/10.2174/1875399X01508010025
Comments on the Quality of English LanguageThe use of the English language in the text needs significant improvement.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors gave very brief answers to most of the questions.
What is the value for : ”The level of accuracy of this model”. Where is the accuracy of this model evaluated (statistically) in the paper? What metrics did you used to measure the accuracy of “the model”? . For a better understanding, look carefully at the models created in your reference article [15]
In Abstract section, the authors mentioned that: “Conclusion. The application of the xGOT metric as a representation of the performance during matches provide a better understanding the characteristics of soccer players or teams.” This conclusion is not is supported by the results.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsDear authors,
Thanks for the corrections. Your manuscript is now eligible for publication. Only the problem with overlapping columns in Tables 1 and 3 still persists, at least in the file I download from the system.
Comments on the Quality of English LanguageMinor corrections may be required to further improve the quality.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsI am not satisfied with most of the answers/modifications that the authors have given. The article does not present/develop a model (as it claims) but analyzes data from the two leagues, which may be interesting for readers
Comments on the Quality of English LanguageMinor editing of English language
