The Exchange 2010 management tools are not required to run MessageStats gatherings but below are a few of the Prerequisits.
For Exchange 2010, ensure that you are using MAPI & CDO version 6.5.8153.0 or later. If you already have a version of the MAPI Download installed, you must remove it before installing the new version. The Microsoft MAPI installer does not upgrade, nor does it warn you if you try to install MAPI & CDO without removing the previous version.
Microsoft PowerShell 2.0
For Exchange 2010, you must also install Microsoft PowerShell 2.0 on the servers that host the MessageStats task processors.