I work as a senior engineer in a software project (~3 years old). Recently, a new engineer was added to work with me for a couple of months to help resolve some of the issues (bug fixes) and enhance the tool. This addition was because of the work load and a schedule rush.
While I was happy to train him and help him come up to speed, I see that he is rushing into doing things to wind up his tasks quickly at the expense of compromising our work quality. Given the state of our project, I prefer permanent solutions to workarounds, good, formatted, refactored code to temporary code patches as I will have to deal with the incurred technical debt later. Though, he is good in trouble shooting issues, I believe not enough time is being spent in learning the tool features (high level) and comprehending existing code.
I informally review his code changes and at most times, find that they require more effort or optimization before his tasks can be considered complete. (the review comments, rework done etc., are not documented, hence my leads are not aware of the extra work that I have to put in to close his tasks).
My manager seems to be very pleased by the fact that he is completing more tasks despite being new to the team but I think code quality and not the number of tasks, is a valid metric to measure a developer's work. I am trying to train him in building code correctly. I have asked him not to rush and to improve his work quality but I don't see much improvement. How can I communicate this to my management as a feedback without sounding as 'a jerk who is jealous of the new team member's performance'?
EDIT : He is not faster than me. As he is new (learning phase), he is being assigned simpler tasks while I work on critical, complex tasks. So it is not the case where I feel threatened. But I am concerned that he is not using this time period effectively to learn things as he seems focused on claiming completion. This would become a problem to me when he gets assigned bigger or complex tasks soon as I wouldn't be able to accommodate helping him with his tasks in my schedule.