这个句子我认为可以分析为动名词分句做主语和表语，理由如下：

现在大家对动名词分句的认定一般分为三种形式：

1) Him stupidly missing the penalty lost us the game.

2) His stupidly missing the penalty lost us the game.

3) His stupid missing of the penalty lost us the game.

第一个句子是宾格动名词形式，但是，在主语为名词的时候，英语分不出主宾格，所以就会出现这样的例子：

Bill eating ice cream is not a pretty sight.

在该句中，eating被认为是中心词。这在夸克语法也有说明If the -ing clause has a subject, the item realizing the subject may be in the genitive case or otherwise in the objective case (for pronouns having a distinctive objective case) or common case (for all other noun phrases).

类似的例句我引用Aarts 文章：

[The deliberate sinking of the ship] was a criminal act.

[The navy deliberately sinking the ship] was a criminal act.

第一个例句是 verbal nouns heading noun phrases，第二个例句是verbs heading clausal structures。

大家传统上称ing词为动名词，但Aarts认为：We follow many modern grammars which prefer to regard structures headed by “verbal gerunds” like those in (4–6) as nonfinite clauses (see e.g. Quirk et al. 1985: 1063–64; Huddleston and Pullum et al. 2002: 80–83, Chap. 14; Aarts 2011: 221–31).

当然，蒋老师分析为分词定语是一种最常用的现象，但这里应该予以区分，比如下面例句：The young lady sitting next to you was wearing the T-shirt … [DI-B54 #64] (37) The traffic you are worried about is the traffic going towards London. [DL-B27 #40]  （these clauses function as modifiers within noun phrases. ）

如何区分动名词还是分词，恐怕还是要从句法和语义着手，首先是看其语法功能，是名词位置还是形容词副词位置，其次，看ing句本身的语义问题。大家都知道，动名词没有明显的时间性，表示的往往是一种抽象的性质，和分词的时间性区别明显。在时和体上是中立的。其效果就是将分句事件提升为类型范围级别，并从具体的上下文（词汇语法上）推导出其作为事件标记的特性。

一家之言，仅供参考！